Alternatives to KumoMTA
Compare KumoMTA alternatives for your business or organization using the curated list below. SourceForge ranks the best alternatives to KumoMTA in 2026. Compare features, ratings, user reviews, pricing, and more from KumoMTA competitors and alternatives in order to make an informed decision for your business.
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Greatmail
Greatmail
Dependable cloud based email hosting with spam filtering, antivirus protection, generous storage and webmail. Compatible with Outlook and all other POP3/IMAP clients. High volume SMTP service for responsible senders. Outbound relay service for transactional messages, email marketing campaigns, newsletters and other applications. Dedicated email servers, clustering and multiple IP load balancing for high volume senders. Fixed monthly cost with unlimited sending and reputation monitoring. Greatmail is an email service provider (ESP) specializing in business class email hosting, SMTP hosting and email servers. For ISPs, application programmers and cloud developers, we also provide custom solutions including dedicated IP servers and process specific, load balanced configurations with multiple servers. -
2
SMTP.com
Ziff Davis
Reliable SMTP relay and email delivery services. Powerful email delivery services that enable you to send and track high volume emails effortlessly. Integrate and start sending in minutes. All your transactional, email relay and email delivery needs under one roof. Whether you need a low-latency email delivery provider for your transactional emails, scalable infrastructure for high-volume sends or reliable backend solution for your marketing campaigns, SMTP is built to deliver. Reputation Defender is SMTP’s proprietary technology that uses big data to proactively monitor your email list health and safeguard your domain and IP reputation among ISPs by suppressing bad emails in your sends from hard and soft bounces. This ensures your delivery rates and inbox placement incrementally gets better over time.Starting Price: $25 per month -
3
PowerMTA
Bird
PowerMTA is an enterprise-grade email message transfer agent (MTA) software for sending high-volume, business-critical emails. PowerMTA can be run on your own server or in any public cloud such as Amazon Web Services or Microsoft Azure. With unmatched reliability and powerful analytics, PowerMTA gives you total control of your email sending. Improve performance, deliverability, and team efficiency with a simple set up, a small hardware footprint, and robust analytics. Try PowerMTA with Signals today, with volume pricing starting at $8,000 per year. PowerMTA includes SparkPost Signals, offering a complete view of your email sending. Analyze per-domain, per-campaign, and even per-recipient performance, allowing you to optimize your sending and prevent problems before they occur. PowerMTA provides unsurpassed delivery and performance in a stable SMTP environment. High-speed sending with total control.Starting Price: $8000 per year -
4
Kerio Connect
Aurea
Secure, enterprise-style email, calendar & collaboration without the high cost. Kerio Connect delivers all the features and functionality for collaboration and messaging solution without the complexity and high price tag of other systems. Email is integrated with shared calendars and scheduling, contacts management, tasks, notes, shared and public folders, and instant messaging. Synchronize messages by direct push to your choice of mobile device via Microsoft ActiveSync. Instant Messaging is XMPP-compatible and can be used from various 3rd party chat/IM applications on desktop and mobile phones. You can install Kerio Connect in 10 minutes and users can be up and running in just 10 minutes more. Kerio Connect can be deployed on-premises or in partner-hosted cloud environments. Deploy for users on Mac, Windows, or Linux; plus full support for Outlook (Windows and Mac) and many other IMAP or POP compliant email clients.Starting Price: $36.50 -
5
Alinto
Alinto
Alinto was born in 2000 as a result of Philippe Gilbert’s vision, whose risk paid off! Bringing together a team of passionate developers and experts in cloud messaging, he innovated the sector with the deployment of the first messaging platform, with a Cloud based email solution in Europe, and the first web based email accessible from a mobile phone. We then became a major player in the European digital arena. As a software mail server provider, our R&D, Marketing and Support teams are committed to adopt an approach focused on availability and proximity. In fact, this is much more than an electronic communication solution, as personalized care and solutions are adapted to your real requirements and needs. Besides, our experts are always available to help. Whether you’re a telecom operator, an internet service provider or an IT specialist, we are here for you. -
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YUDOmail by Inbotiqa
Inbotiqa
Inbotiqa's YUDOmail Intelligent Business Email solution provides automation and case and workflow management for Enterprise clients to cut costs, reduce risk, increase productivity and realise revenue growth, while analytics enables unprecedented management insights. The enterprise-grade email and workflow system focuses on high-volume shared mailboxes containing business-critical instructions. 100% execution is realised, with turnaround times reduced, as no email is missed. Teams can focus on tasks of value instead of managing email, thereby dramatically improving customer service and productivity levels. Accountability is ensured, while tracking and traceability generate a clear audit trail for organisational memory and compliance and audit purposes. Inbotiqa’s Intelligent Business Email solution transforms the world’s primary business communication channel. -
7
Microsoft Exchange
Microsoft
Work smarter with business-class email and calendaring. Exchange helps you collaborate on your critical documents and gives you a focused inbox that prioritizes important messages and adapts to your work style, so you can get more done–faster. Get access to a more personalized inbox with helpful features and a smarter, more organized way to view and interact with email. Search enhancements give you faster and more complete results. With Add-ins, get powerful customization and extensibility, which connect you to modern services and internal line-of-business applications. Organize your time with a calendaring system that goes beyond basic scheduling of appointments and commitments. Automatically capture events from email such as flights and hotel reservations, and get suggestions about where to meet based on your location. Microsoft Exchange Online offers a hosted email service for business. Exchange Online helps protect your information with advanced capabilities. -
8
Kolab Now
Apheleia IT AG
Secure and private email, calendars and more. 100% Free & Open Source Software (FOSS). Open standards and formats used for all storage and communication. No vendor lock-in. All data stored under Swiss jurisdiction. User data never transmitted to any third party without explicit consent. GDPR, HIPAA and PCI compliant. Built secure from the ground up. Supports perfect forward secrecy (PFS). End-to-end encryption available. No back doors. Our documentation contains answers to most frequently asked questions and much more. Are you looking for an instant answer to your question or a quick solution for your problem, our Knowledgebase is where you will likely find it. If you can’t find the answer in our documentation, you can always contact support.Starting Price: $9.90 per month -
9
XgenPlus
Bharat Sync Technologies Pvt. Ltd.
XgenPlus is a next-generation, feature-rich, and highly secure email solution designed to meet the growing communication needs of businesses, enterprises, and individuals. Developed by Bharat Sync Technologies Pvt. Ltd., Xgen Email stands out as the first email service in the world to support Internationalized Domain Names (IDN), enabling users to create email addresses in multiple Indian languages such as Hindi, Gujarati, Tamil, Telugu, Punjabi, and Urdu. With cutting-edge security features, real-time tracking, advanced collaboration tools, and seamless mobile and desktop integration, Xgen Email ensures that users get the most efficient, private, and productive email experience. Whether you're a startup, a large enterprise, or an individual professional, Xgen Email is the best choice for a secure, smart, and efficient email solution.Starting Price: Free -
10
Oracle Communications Messaging Server is a standards-based Internet messaging server designed for high-capacity, reliable message handling for service providers and their customers. Messaging Server provides support for several email protocols and can manage embedded text, sound, graphics, video files, and other files and formats.
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Matrix Platform is designed to improve productivity and collaborative working process across departments and teams. We have provided group email platforms to shipbrokers, charterers and commodity traders for over 30 years. Integrated high volume secure email and fax handling. Simple or Classic User Interface – to ensure the right user experience. Full integration available with S&P, Chartering, Offshore and Fixtures modules. The matrix allows groups, teams, and departments to work collaboratively to increase productivity. ‘Rules’ are applied to incoming and outgoing messages ensuring that the right workgroups and individuals ‘view’ each message. The system proactively alerts you to emails based on your chosen keyword. Enables users to prioritize vital revenue-generating commercial messages. All messages marked as read on your smartphone/tablet will appear as read on the Matrix client as well.
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Eudora Internet Mail Server
Eudora Internet Mail Server
Completely rewritten relay restrictions with an easier to use interface that gives finer control over relay security. New domain name resolver (DNR), EIMS now has it's own DNR, which works around bugs in the Open Transport DNR and performance problems with the OS X DNR. The new DNR does not currently support non-recursive DNSs. SMTP Submit port, this is a second SMTP port running on TCP port 587 by default. It currently works exactly the same as the standard SMTP port. This is handy for clients that are stuck behind an ISP that blocks port 25 access. Sending Setup option for maximum recipients per message. Expand SMTP Addresses option, you can now turn this off, with EIMS 3.1 and earlier it was always on. The SMTP server (both port 25 and 587) now reports Telnet connections and connections that look like port scans (connections where no data is sent and it doesn't time out).Starting Price: Free -
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Haraka
Haraka
Haraka can serve thousands of concurrent connections and deliver thousands of messages per second. Haraka and plugins are written in asynchronous JS and are very fast. Haraka has very good spam protection (see plugins) and works well as a filtering MTA. It also works well as an MSA running on port 587 with auth and dkim_sign plugins enabled. Haraka makes no attempt to be a mail store (like an exchange or postfix/exim/qmail), an LDA, or an IMAP server (like Dovecot or courier). Haraka is typically used with such systems. Haraka has a scalable outbound mail delivery engine built in. Mail marked as relaying (such as via an auth plugin) is automatically queued for outbound delivery. Haraka's plugin architecture provides an easily extensible MTA that complements traditional MTAs that excel at managing mail stores but do not have sufficient filtering.Starting Price: Free -
14
iRedMail
iRedMail
The right way to build your mail server with open source softwares. Works on CentOS Stream, Rocky, Alma, Debian, Ubuntu, FreeBSD, OpenBSD. With iRedMail, you can deploy an OPEN SOURCE, FULLY FLEDGED, FULL-FEATURED mail server in several minutes, for free. We did the heavy lifting of putting all the open source components together and applying best practices. Our product does all the major tasks for you. Furthermore we offer professional support to back you up in case you have some problems. You have all personal data on your own hard disk, you can control the email security, inspect transaction log. No other organization can see the content of all messages. All components used in iRedMail are open source softwares, and you get the bug fixes and updates from the Linux/BSD venders you trust. iRedMail is the right way to build your mail server with open source softwares.Starting Price: Free -
15
MDaemon Email Server
MDaemon Technologies
The MDaemon Email Server was one of the first Microsoft Exchange alternatives offered to businesses around the world. It has been developed with the ongoing input from IT professionals seeking an easy-to-use, reliable, and secure mail server that does not require expensive administration or impose high per-user costs. It simplifies messaging and collaboration with a focus on security and privacy, an intuitive, user-friendly web mail design and by offering administrators Mobile Device Management, Business Instant Messaging, Document Sharing, and other enterprise-class features that can be managed with minimal support. MDaemon Email Server supports IMAP, SMTP, and POP3 protocols, and features include: integrated webmail with IM and document sharing, Outlook support, compromised password alerts, color-coded log files for quick and easy troubleshooting, customizable email policy setting to fit your unique network environment, Mobile Device Management, Account Hijack Detection, and more.Starting Price: $360 per year -
16
Axigen
Axigen Messaging
Offer your customers secure, business-level email hosting with various value added services. An excellent solution for SPs, suitable for thousands to millions of users. Acquire new customers by offering a premium email server solution with a high degree of flexibility, allowing you to automate it within your existing infrastructure. Manage your email, organize and share calendars, sync your mobile devices, all based on a secure and powerful mail server. The perfect answer for businesses of all sizes. Axigen is quite knowledgeable, out of the many hats it wears, take a peek inside and choose what fits you. Manage your email and get stuff done easily with calendars, tasks or notes. Enjoy desktop usability in your browser via keyboard navigation and shortcuts, drag-and-drop, "live" email list view, frequent folders, email filters, out-of-office messages, individual blacklist / whitelist.Starting Price: $266 per year -
17
Scalix
Scalix
Offer a high value Outlook experience with push email, PIM, group calendaring, free/busy services, public folders, delegation, and more. Increase margins with lower server counts and compelling subscription pricing. Reduce your licensing costs and leverage your teams' existing skills with a Linux-based platform. Scalix starter packs are robust, single-server messaging solutions designed to provide smaller businesses and organizations with a full featured email and collaboration solution. Scalix small business edition is our single-server solution designed for small businesses. It includes a rich package of business functionality including a means to instantly recover deleted items on a user-specific basis, wireless device support and more. -
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Mailtraq
Mailtraq
Mailtraq Professional mail server software is the complete email server for business. It does everything you need at a great price and without hassles. Mailtraq is the ideal Microsoft Exchange Alternative: easy to deploy and simple to manage. Low license cost, no server-CALs, and stability in operation make Mailtraq email server software the choice for all SMB and SOHO businesses. Email is at the heart of your company or organization, and where those messages are stored is of vital importance to the long-term health of your firm. There is a degree of hassle and expense involved in running your own email server but it gives you complete physical control over who has access to your email. If you use your ISP's service then their system administrators can see and read your messages. Similarly, if you use a SAAS supplier for a hosted email service, and if you use a Cloud provider you not only don't know who is reading your email, but don't even know where in the world it is kept. -
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SEDNA
SEDNA Systems
Cut down email volume by up to 95% and get one source of truth for all conversations, data, and documentation through shared team inboxes. Unlike siloed email accounts, SEDNA gives team members controlled transparency of all correspondence, attachments, and actions taken within a project or message thread—along with quick composition and sharing capabilities—for more efficient communication and effortless collaboration. Each email within a team inbox has its own activity panel to host internal conversations, contextual data, and time-stamped activity that enables team members to work with—and around—one message in place of forwards, reply-alls, and cc’s that bloat email volume. The Activity Panel lets you see automatically generated or manually applied message details like category tags, job references, and people involved, as well as who viewed the message, who replied, and how so. And collaboration is easy with the ability to tag others and add comments for real-time discussion. -
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Purplefish
Purplefish
Purplefish enables high-volume recruiters to automate phone screenings using human-quality voice AI, providing candidates with a fast and consistent experience. By leveraging AI agents, recruiters can efficiently screen ten times the candidates in one-tenth the time. Purplefish is building enterprise-grade AI agents for high-volume recruiting at large staffing agencies and corporations. -
21
IceWarp
IceWarp
The only office rule is, there is no office. Business email, TeamChat for project teamwork, real-time office document collaboration and online meetings. All in our secure cloud and for half the usual cost. Chat in teams organized around projects, upload files, mention coworkers, comment on posted emails, pin important posts. Integration with email enables sharing received messages directly to TeamChat room for colleagues‘ attention. Skyrocket your office work effectivity with Desktop Client and Desktop Office documents on Windows as well as Linux devices. Get the complete Suite, or choose only the app you need.Starting Price: $312.00/year/user -
22
WinGate
WinGate
WinGate Proxy Server is a highly capable HTTP Proxy server, SOCKS server, integrated Internet gateway and communications server designed to meet the access control, security and communications needs of today's businesses. In addition to a comprehensive range of features, WinGate Proxy Server's license options provide you the flexibility to match your needs to your budget, whether you need to manage an enterprise, small business, or home network. WinGate Proxy Server will share most types of Internet connection, allowing multiple users to simultaneously surf the web, retrieve their email, or use other internet programs, as if they were directly connected to the Internet. Whether it is a simple dialup modem or high speed fibre, WinGate Proxy Server can help to make the most out of the connection. WinGate Proxy Server supports a wide variety of Internet protocols, allowing applications such as Web browsers, messaging software, FTP and SSL.Starting Price: $109.95 one-time payment -
23
Synology MailPlus
Synology
Improve team efficiency with an on-premises email solution that ensures data ownership, security, and reliability. Set up mailboxes based on advanced filters and custom labels to keep abreast of what matters to you. Turn off conversation mode and split email threads into separate messages to work the way you are used to. Invite work partners to share the same mailbox and make progress on projects together. Host multiple email domains on a single server and configure each independently. Configure different login methods, daily email traffic quotas, email delivery, and other policies for users and groups. Assign administrative rights by function to distribute the administrative workload. Visualize the threats against your team's inbound and outbound emails in simple and clear charts. Detect spam and learn more about email threats with the high-performance Rspamd engine. -
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mailcow
mailcow
mailcow: dockerized is an open source groupware/email suite based on Docker. mailcow relies on many well known and long used components, which in combination result in an all around carefree email server. Each container represents a single application, connected in a bridged network.Starting Price: Free -
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Mirth Connect
NextGen Healthcare
Mirth Connect by NextGen Healthcare is a leading open-source healthcare integration engine designed to optimize interoperability across diverse healthcare systems. It supports various messaging standards, including HL7, FHIR, and DICOM, enabling seamless data exchange between disparate applications. The platform offers a user-friendly interface with both drag-and-drop and advanced scripting capabilities, allowing users to efficiently build, test, and deploy interfaces tailored to their specific needs. Mirth Connect is platform-agnostic, ensuring compatibility with various systems and technologies, and is built to handle high-volume, high-throughput workloads, making it suitable for organizations of all sizes. For those seeking enhanced features and dedicated support, Mirth Connect Premium provides advanced capabilities such as SSL and certificate management, FHIR connectors, and access to comprehensive training and certification programs. -
26
MailEnable
MailEnable
MailEnable provides an end to end solution for providing secure email and collaboration services. A recent independent survey reports MailEnable as the most popular Windows Mail Server Platform in the world. Whether you are a hosting company providing email services to thousands of end users or a small business with a single domain, MailEnable provides a solution that will impress your mail users. MailEnable provides Windows Mail Server software with features comparable to Microsoft Exchange. It provides powerful messaging services like Exchange ActiveSync, IMAP, SMTP, POP3 and collaboration tools such as calendaring (CalDAV), contacts (CardDAV), tasks and notes.Starting Price: $349 -
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NethServer
NethServer
Analyzes all web traffic and blocks selected websites via HTTP and even HTTPS using Squid proxy. Integrated with ClamAV antivirus and site blacklists. Multi-domain web server with ready LAMP stack. Virtual hosting allows to host multiple domain names on a single server. Based on NextCloud provides universal access to your files via the web, your computer or your mobile devices, wherever you are. Provide a private Slack-alternative with Mattermost. Open source messaging platform that enables secure team collaboration. Modern and powerful web interface based on Cockpit that simplifies common administration tasks, very easy and fast installation. Based on CentOS/RHEL, a widespread and popular server distribution, trusted by routine security updates, and rock solid stability.Starting Price: €48 per year -
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hMailServer
hMailServer
hMailServer is a free, open source, e-mail server for Microsoft Windows. It's used by Internet service providers, companies, governments, schools and enthusiasts in all parts of the world. It supports the common e-mail protocols (IMAP, SMTP and POP3) and can easily be integrated with many existing web mail systems. It has flexible score-based spam protection and can attach to your virus scanner to scan all incoming and outgoing email.Starting Price: Free -
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GMS (Gordano Messaging Suite)
Gordano
You're a growing business, and you need to stay connected: you need email. But you're stretched thin, facing the every day challenges. You need help. You have come to the right place. GMS has been around since the beginning of email. We have got plenty of experience in understanding our customers and providing what they need. We're like you: we care about your business. We keep it simple: we don't like jargon, and we don't like confusion. With GMS the message is clear: the ideal email solution for small businesses, with all the support you could ever want. Once part of the Cloud, businesses and individuals no longer have to worry about power requirements, space or software updates. Cloud computing negates the need for physical storage and maintenance, meaning the total cost of ownership is significantly lower. -
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qmail
qmail
qmail is a secure, reliable, efficient, simple message transfer agent. Security isn't just a goal, but an absolute requirement. Mail delivery is critical for users; it cannot be turned off, so it must be completely secure. qmail's straight-paper-path philosophy guarantees that a message once accepted into the system, will never be lost. qmail also optionally supports maildir, a new, super-reliable user mailbox format. Maildirs, unlike mbox files and mh folders, won't be corrupted if the system crashes during delivery. Even better, not only can a user safely read his mail over NFS, but any number of NFS clients can deliver mail to him at the same time. qmail is vastly smaller than any other Internet MTA. Other MTAs have separate forwarding, aliasing, and mailing list mechanisms. qmail has one simple forwarding mechanism that lets users handle their own mailing lists. -
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MailChannels
MailChannels
Secure and deliver email at scale. Use MailChannels to uncover bad actors and prevent spammers from taking advantage of your infrastructure. Monitor outgoing email messages for spam and unusual sending activity. Protect your customer inboxes against spam, phishing, and other email threats. A powerful, intuitive interface makes managing your customers simple and efficient. We operate across multiple clouds and minimize single points of failure to keep our services online, all the time. Get a real human response to your ticket within 30 minutes or less, 24/7/365. MailChannels Outbound Filtering is a cloud-based SMTP relay service which identifies and blocks spammers to ensure reliable email delivery. With Outbound Filtering, you can eliminate email delivery problems caused by IP address blocklisting. Automatically shut down compromised accounts and scripts to improve your security.Starting Price: $79.99 per month -
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Videris
Blackdot Solutions
Videris is an enterprise-grade open-source intelligence platform designed to help organizations collect, analyze, and visualize public and deep-web data to uncover hidden risks and networks. It enables users to search across corporate registries, surface web, deep and dark web, and social media, then layer internal or niche data sources for enriched context. Featured capabilities include AI-driven risk analysis, automated entity disambiguation, network visualization tools that map connections between people, organizations, and events, secure browsing of live web content without revealing investigator identity, and automated reporting that preserves evidential integrity with full sourcing and audit logs. It offers two modes: an “Automate” workflow for high-volume, repeat investigations and a “Investigate” mode for expert-driven deep dives into complex cases. -
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Poste.io
analogic
You can have a fully functional mail server installed in a few minutes, mostly waiting for scripts to do the work. The whole package is designed with reasonable defaults to get you up and running quickly, without having to know the internals and without making decisions that could break the email system. User data and configuration is strictly separated from binaries. User database is stored in SQLite database - in file. This makes Poste.io fully compatible with external storage. Migration, backups or updates are therefore very easy and mostly consist of files manipulation. Poste.io has been built from the ground up with security in mind. Internet history is littered with painful security incidents, so we traded old email client compatibility and insecure authentication methods for features that meet today's for features that meet modern security requirements.Starting Price: Free -
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Cyrus IMAP
The Cyrus Team
Cyrus IMAP is an email, contacts and calendar server. Cyrus is free and open source. Features: Speed Security Efficiency Search CardDAV and CalDAV support Robust data storage Replication Scalable for large installations Flexible filtering support through Sieve Supports antivirus and antispam toolkits Handles deliverability: SPF, DKIM, DMARC Extensive authentication options, through Cyrus SASL JMAP support Long list of supported standardsStarting Price: Free -
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GreenArrow
GreenArrow Email
It’s time for smarter tools and more transparent data so your messages reach their destination. Plus, more insight into subscriber activity will help teams fine-tune messages, make connections, and grow business. It’s time to turbo-charge your technology. Need to send 8 million messages per hour from a single server? High-speed, high-volume, we’ve mastered it. Consider your lofty goals reachable. It’s time for a team who can actually help you. We’re not just problem-solvers at GreenArrow. We’re solution coordinators. We tackle the tough stuff, but we also hand you tools and knowledge so you get smarter about your software. GreenArrow’s premium, high-performance solutions and unmatched support team can help you grow business and build better subscriber relationships.Starting Price: $600 per month -
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Citadel
Citadel
Email, collaboration, groupware, and content management - up and running in minutes, on your own hardware, or in the cloud. Citadel is easy, versatile, and powerful, thanks to its exclusive room-based architecture. No other platform seamlessly combines so many different features using this familiar and consistent metaphor. Citadel is 100% open source software using the GNU General Public License. It's not a crippled, cut-down version of some expensive "enterprise" edition. The software you download here is the very best available, and it's all free software.Starting Price: Free -
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Modoboa
Modoboa
Regain your independence and protect your privacy by installing your own email server. It takes less than 10 minutes! Create your mail server for free in less than 10 minutes with Modoboa When it comes to create a mailbox, you generally have several solutions: - Use the services offered by Internet providers (Orange, Vodafone...) of infrastructure providers (OVH, Gandi...) with a monthly or annual subscription. However, customization and configuration possibilities, domains and mailboxes number are limited. - Use the services of free email providers (Gmail, Live, Yahoo...) which are limited and your data is used for commercial purposes. - Install your own email server, which requires important technical knowledge to setup and configure the system. Modoboa is an alternative to those 3 options. It frees you from dependence on email providers and makes accessible to all the creation his own secure email server. The whole thing, in less than 10 minutes and freely.Starting Price: Free -
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CommuniGate Pro
CommuniGate Software
Our end to end Unified Communications technology begins with the platform CommuniGate Pro. The system enables large scale Unified Communications with open API’s for integration into business applications. CommuniGate Pro scales dynamically to 100’s of millions of accounts. Ideally suitable for “Nation” scale alert systems, multimodal communications within web applications, or compartmentalized high-security network topologies. However, big scale does not mean trade-offs on efficiency or reliability. The platform is extremely agile for resilient applications in military or embedded environments. CommuniGate Pro is approved for governmental agency use in Europe and in the USA. Military, transportation and research center use is legendary for mind bending stability with uptimes like VMS. CommuniGate Pro enables banks to deploy mail to millions of clients for online self care while respecting compliance regulations. The signaling features of the server can be deployed in a hybrid system. -
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Opt-Inbox
Sendio
Sendio’s Opt-Inbox is a proprietary sender management process, acting on messages having cleared email security, which would otherwise be released into a user’s inbox, ensuring that recipients only receive messages from desirable sources, whether from individuals or subscriptions, leaving the new yet undecided sources to the recipient’s discretion in a queue separate from the usually messy quarantine queue. Despite being protected by advanced email security systems, many inboxes continue to be inundated with countless security-cleared messages comprised of persistent sales pitches and marketing communications, distribution lists and bulk sources. Separating harmful messages in the quarantine queue from nuisance and potentially desired ones is increasingly difficult. This can become particularly troublesome for executives and professionals who can’t afford to overlook an important email and find out later they had a desirable message (false positive) in their cluttered quarantine queue.Starting Price: $795 per year -
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Boomerang
Baydin
Schedule an email to be sent later. Easy email reminders. Boomerang for Gmail lets you take control of when you send and receive email messages. With Boomerang, you can write an email now and schedule it to be sent automatically at the perfect time. Just write the messages as you normally would, then click the Send Later button. Use our handy calendar picker or our text box that understands language like "next Monday" to tell Boomerang when to send your message. We'll take it from there. Want a cleaner inbox, but don't want to lose track of important messages? Use Boomerang to take messages out of your inbox until you actually need them. Just click the Boomerang button when you have an email open, and choose when you need it again. Boomerang will archive your message. At the time you choose, we'll bring it back to your inbox, marked unread, starred or even at the top of your message list. -
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OpenText GroupWise
OpenText
OpenText GroupWise is a secure, enterprise-grade messaging and collaboration platform that combines email, calendaring, contacts, and scheduling into a single, flexible system. It is built for organizations that require strong security, compliance, and reliability across highly regulated industries such as government, education, utilities, and healthcare. The platform enables teams to customize the user interface, integrate with systems like Microsoft Exchange and Active Directory, and centrally manage contacts, address books, and shared calendars. GroupWise includes intelligent scheduling tools, travel-time adjustments, and collaboration features that help streamline workflows and improve daily productivity. Its security measures—such as multifactor authentication, encryption, and gateway protection—ensure that sensitive communications stay protected. -
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SmarterMail
SmarterTools
SmarterMail is the ideal Microsoft Exchange alternative. It’s the only business email server on the market that offers native support for Exchange protocols: MAPI, EWS, and EAS, without requiring any additional software or plug-ins for Microsoft Outlook or other desktop or mobile clients. It delivers all the features of Exchange at a fraction of the cost. SmarterMail also includes audio/video group chat and Online Meetings for team collaboration at no extra charge. Its newest feature, the SmarterMail Marketplace, enables seamless integration with platforms like OnlyOffice, Collabora, and AI tools such as OpenAI’s ChatGPT. Available for both Windows and Linux, SmarterMail has lower hardware requirements, superior stability, and reduced maintenance costs. It’s the perfect solution for businesses of any size or industry seeking Exchange-level functionality, without the high costs.Starting Price: $500.00/one-time -
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OpenSMTPD
OpenSMTPD
OpenSMTPD is a free implementation of the server-side SMTP protocol as defined by RFC 5321, with some additional standard extensions. It allows ordinary machines to exchange emails with other systems speaking the SMTP protocol. Started out of dissatisfaction with other implementations, OpenSMTPD is a fairly complete SMTP implementation. OpenSMTPD is primarily developed by Gilles Chehade and Eric Faurot, with contributions from various OpenBSD hackers and members from other communities.Starting Price: Free -
44
Mojaloop
Modusbox
The world’s first open-source platform for interoperability in a real-time payment network. We’re driving low-cost digital payment services for banks, companies, governments, and people everywhere. Check out our contributions on Mojaloop.io. Unbanked populations typically rely on low-value, high-volume transactions, making them less attractive customers for most banks. As a secure open-source platform, Mojaloop promotes interoperability for everyone, all classes of Digital Service Providers (DSPs), and the customers they serve. With a purpose-built reference architecture that embodies the level one project principles, Mojaloop is a cost-effective solution for real-time payment and settlement management. Payment hub operators can leverage the technology to deliver transformational and inclusive financial services into their markets. Available to any licensed DFSP in the country including banks and licensed non-banks. -
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Exim
Exim
Exim is a mail transfer agent (MTA) used in Unixllike operating systems. The first version was written in 1995 by Philip Hazel for use in the University of Cambridge Computing Service's e-mail systems. Exim is distributed under the GPL, and therefore is free to download, use and modify. Exim somewhat resembles Smail 3, but it has diverged and now surpasses it in user friendliness and flexibility. They both follow the Sendmail design model where a single main binary controls all the facilities of the MTA. This monolithic design is considered by some to be inherently less secure and slower, but despite this, Exim's security record is much better than Sendmail and comparable with Qmail and Postfix, as is its speed. In advanced areas such as queue handling, address routing and testing, it exhibits excellent performance. Exim doesn't have a Graphical User Interface (GUI) to help you configure it, but some Linux distributions add one. -
46
Horde
Horde
Horde is the most flexible groupware on the planet, and that makes it the perfect platform on which to build your business productivity software. Horde connects to (and officially supports) more backends (all the leading SQL, LDAP, IMAP, Sieve, SMTP, cache platforms available today) than any other open source groupware system. This means you can continue to use your existing userbase and your users do not have to remember any additional passwords. Horde's feature set rivals the largest enterprise email systems. We have an incredible feature set that compares favorably against any competition in our primary apps (mail, calendar, address book), and even more in our secondary apps (time tracking, wiki, ticketing, and more).Starting Price: Free -
47
OpenText Core Email Continuity
OpenText
The OpenText Core Email Continuity solution ensures continuous access to email even when your primary mail infrastructure goes down, by automatically redirecting messaging to a secure web portal or Outlook via POP/IMAP, allowing users to read, reply, forward, compose, and send email normally during outages. It provides up to 30 days of stored inbound messages, preserving recent email history. During a mail-server outage, incoming messages are spooled at the spam filter, and users are automatically directed to the continuity service; once the primary server returns online, all email activity (sent items, replies, forwards, new messages) syncs back automatically to the main mailbox, preserving continuity. It requires no additional hardware, it auto-provisions through a central portal, and runs transparently until needed. Access can be from any device, anywhere, via web or standard email clients. -
48
Dovecot Pro
Open-Xchange
Dovecot Pro is a full-service email platform that delivers dynamic scalability, high performance, efficient utilization of hardware, and outstanding support to the world’s largest Telcos, ISP's, and Hosters. With a marketshare of 76% of installed email backends, customers trust the performance of Dovecot Pro. Efficient hardware utilization and advanced monitoring tools for statistics and administration reduce ownership costs and save time and maintenance costs. In addition, Dovecot Pro scales up and out to hundreds of servers and millions of users and multiple physical sites. Its stateless native architecture offers maximum flexibility as each major component can be deployed on its own dedicated node. Dovecot Pro provides industry-leading support for all email standards necessary to provide both Mail Delivery Agent functionality (via LMTP and Sieve), and to facilitate mail retrieval by mail clients (via IMAP and POP3). -
49
‘nflow
'nuffsaid
Get your actual work done. A smart space for your work apps. ‘nflow helps you take back control and saves you 2 hours per day. The typical knowledge worker now spends 4.1 hours/day on email. And if you’re a Slack user, figure 70 messages per day. And that’s not counting the rest. ‘nuffsaid integrates your email, chat, Salesforce, LinkedIn, SMS and more into a single customizable view. Your AI assistant automatically prioritizes your email, chats, meetings and tasks, and eliminates tedious activities like data entry. Stop switching between your task list, email, and calendar. With ‘nuffsaid you can drag and drop messages and tasks into your calendar, then back to your inbox. The days of a separate task list are gone. Easily convert messages and meetings into tasks, assign them, and get auto-alerts when tasks are overdue. Can't remember where a conversation happened? Quickly find messages, attachments, tasks, and appointments across all your tools in a single search engine. -
50
Mixmax
Mixmax
Get more replies, book more meetings, and ensure nothing falls through the cracks. Powering fast growing companies that care about customer experience. Win more replies, meetings, and deals with smart messaging. Improve the customer experience and increase team engagement. Know exactly which candidates open your email, and what content they viewed. Increase sales performance, align your reps, and automate busywork. Analyze performance trends and improve process form a bird’s eye view. Open more doors and 10x your productivity without leaving your inbox. Improve CRM hygiene and automate busywork with automatic Salesforce syncing. You'll know as soon as someone opens your message with real-time email tracking & alerts. Know exactly which messages get the most engagement. Compare impact by team, individual, and campaign. Receive alerts on desktop, email or Slack based on the actions you choose.Starting Price: $9.00/month/user
