Cisco Secure Email

Best Self Hosted Alternatives to Cisco Secure Email

A curated collection of the 2 best self hosted alternatives to Cisco Secure Email.

Cloud-based email security gateway that scans inbound and outbound email for spam, phishing, malware and ransomware, using threat intelligence, URL and attachment analysis, sandboxing, policy-based encryption and DLP controls for enterprise email.

Alternatives List

#1
Stalwart Mail Server

Stalwart Mail Server

All-in-one open-source mail and collaboration server with SMTP, IMAP, JMAP, CalDAV, CardDAV, and WebDAV, plus integrated anti-spam and phishing protection.

Stalwart Mail Server screenshot

Stalwart Mail Server is an all-in-one mail and collaboration server built to provide a modern, standards-based alternative to assembling multiple separate components. It combines email delivery and storage, groupware protocols, and built-in security controls in a single, scalable service written in Rust.

Key Features

  • Multi-protocol email support including SMTP, IMAP4, POP3, and JMAP
  • Collaboration protocols including CalDAV, CardDAV, and WebDAV for calendars, contacts, and file storage
  • Integrated spam and phishing defenses, including filtering rules, DNS blocklists, greylisting, and a statistical classifier
  • Email authentication and transport security features such as DKIM, SPF, DMARC, ARC, MTA-STS, DANE, and TLS reporting
  • Flexible backends for storage and search, with support for multiple databases and optional external search engines
  • Built-in web-based administration with real-time stats, queue management, reporting views, and log exploration
  • Authentication options including LDAP, SQL, and OpenID Connect, plus roles/permissions and ACLs
  • Observability via logging/tracing and metrics integrations, with webhook-based event automation

Use Cases

  • Replace a traditional MTA + IMAP store + spam filter stack with a single integrated platform
  • Run a domain email service with modern clients via JMAP while retaining IMAP/POP3 compatibility
  • Provide calendars, contacts, and file sharing for teams using CalDAV/CardDAV/WebDAV

Limitations and Considerations

  • Some advanced scaling and backend options can add operational complexity compared to small single-node deployments

Stalwart Mail Server is well-suited for organizations and individuals who want a secure, standards-compliant email and collaboration platform with modern protocols, integrated protection against abuse, and deployment flexibility from small setups to large clustered environments.

11.2kstars
602forks
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#2
Mailu

Mailu

Mailu is a full-featured mail server distributed as Docker images, providing SMTP/IMAP/POP3, webmail, administration UI, and built-in security and anti-spam features.

Mailu screenshot

Mailu is a simple yet full-featured email server distributed as a set of Docker images. It provides the core protocols needed to run your own mail infrastructure, plus webmail and an administration interface.

Key Features

  • SMTP, Submission, IMAP/IMAP+, and optional POP3 support
  • Multiple webmail options and a built-in administration UI
  • Aliases, domain aliases, custom routing, auto-forward and auto-reply
  • Fetched accounts (fetchmail-style) and ManageSieve support
  • Per-domain delegation, global admins, announcements, and mailbox quotas
  • Security features including enforced TLS, Let’s Encrypt integration, outgoing DKIM, DMARC/SPF, and anti-spoofing options
  • Anti-spam features such as greylisting and auto-learning, plus optional antivirus scanning

Use Cases

  • Hosting email for personal domains or small organizations with a web-based admin panel
  • Running multi-domain mail hosting with delegated per-domain administration
  • Deploying a containerized mail stack with DKIM/DMARC/SPF and spam filtering

Limitations and Considerations

  • Deliverability depends on correct DNS configuration (SPF, DKIM, DMARC, rDNS) and IP reputation
  • Operating a mail server requires ongoing maintenance (TLS, spam rules, storage quotas, and monitoring)

Mailu focuses on providing a complete, containerized mail stack using standard components rather than a full groupware suite. It is designed to be straightforward to deploy and maintain while offering the security and administrative features expected from a modern mail server.

7kstars
960forks
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Why choose an open source alternative?

  • •Data ownership: Keep your data on your own servers
  • •No vendor lock-in: Freedom to switch or modify at any time
  • •Cost savings: Reduce or eliminate subscription fees
  • •Transparency: Audit the code and know exactly what's running