Comparison of mail servers
This is a comparison of mail servers: mail transfer agents, mail delivery agents, and other computer software that provide e-mail services.
Unix-based mail servers are built using a number of components because a Unix-style environment is, by default, a toolbox operating system. A stock Unix-like server already has internal mail, more traditional ones also come with a full MTA already part of the standard installation. To allow the server to send external emails, an MTA such as Sendmail, Postfix, or Exim is required. Mail is read either through direct access or mailbox protocols like POP and IMAP. Unix based MTA software largely acts as enhancement or replacement of the respective system's "native" MTA.
Windows servers do not natively implement email. Windows-based MTAs therefore have to cover the whole set of email-related functionality.
Feature comparison
Authentication
Antispam features
| Mail Server | DNSBL | SURBL | Spamtraps | Greylisting | SPF | DKIM | DMARC | Tarpit | Bayesian filters | Regular expressions | Embedded Antivirus | Embedded Antispam |
| agorum core | ||||||||||||
| Apache James | ClamAV | |||||||||||
| Axigen | , in SpamAssassin | CYREN | CYREN | |||||||||
| Citadel | ||||||||||||
| Courier Mail Server | Clamav | |||||||||||
| Dovecot | ||||||||||||
| Eudora Internet Mail Server | ||||||||||||
| Exim | at build time | at build time | with spamassassin etc. | any | any | |||||||
| FirstClass | Symantec | |||||||||||
| Gordano Messaging Suite | CYREN, Authentium | CYREN | ||||||||||
| GroupWise | ||||||||||||
| Halon | ||||||||||||
| Haraka | with spamassassin etc. | ClamAV, AVG, any via plugins | SpamAssassin, MessageSniffer | |||||||||
| hMailServer | ClamAV | SpamAssassin | ||||||||||
| IBM Notes | ||||||||||||
| IceWarp Mail Server | ||||||||||||
| Ipswitch IMail Server | Symantec, BitDefender | CYREN | ||||||||||
| Kolab | with spamassassin etc. | |||||||||||
| Mailsite | ||||||||||||
| Mailtraq | ||||||||||||
| MDaemon | Cyren, ClamAV | SpamAssassin | ||||||||||
| Mercury Mail Transport System | ||||||||||||
| Microsoft Exchange Server | ||||||||||||
| NetMail | ||||||||||||
| OpenSMTPD | ||||||||||||
| Oracle Communications Messaging Server | with spamassassin etc. | any | any | |||||||||
| Postfix | with spamassassin etc. | |||||||||||
| qmail | ||||||||||||
| Scalix | ||||||||||||
| Sendmail | with spamassassin etc. | ClamAV | SpamAssassin | |||||||||
| SparkEngine | ||||||||||||
| UW IMAP | ||||||||||||
| WinGate | ||||||||||||
| Zarafa | ||||||||||||
| Zimbra | ||||||||||||
| Mail Server | DNSBL | SURBL | Spamtraps | Greylisting | SPF | DKIM | DMARC | Tarpit | Bayesian filters | Regular expressions | Embedded Antivirus | Embedded Antispam |