SMTP Service

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qmail includes the following Simple Mail Transfer Protocol (SMTP) service features:

  • RFC compliant. Complies with RFC 2821 (SMTP), RFC 1123, RFC 1651 (ESMTP), RFC 1652 (8-bit MIME), and RFC 1854 (pipelining).

  • 8-bit clean. Accepts 7-bit ASCII characters as well as 8-bit extended characters.

  • Supports IDENT (RFC 931/1413/TAP) callback. This allows cooperating mail administrators to determine the identity of users abusing the system.

  • Relay control. qmail automatically denies unauthorized relaying by outsiders.

  • Automatic recognition of local Internet Protocol (IP) addresses. Messages to jessica@[192.168.1.3] are recognized as local by qmail-smtpd if 192.168.1.3 is a local IP address.

  • Per-buffer timeouts. Each new buffer of data from the remote SMTP client has its own time limit.

  • Hop counting for detection of looping messages. Messages that pass through more than 100 delivery hops are rejected.

  • Parallelism limit. Using tcpserver, which is part of the ucspi-tcp package, the number of concurrent incoming SMTP sessions can be controlled.

  • Refusal of connections from known abusers. Using tcpserver, specific hosts and domains can be refused access to the SMTP server.

  • Relaying and message rewriting for authorized clients. The RELAYCLIENT environment variable can be used to allow authorized hosts to relay or to modify header fields for specified hosts.

  • Optional RBL support. Using rblsmtpd, from the ucspi-tcp package, access can be denied to known senders of junk e-mail—also known as spam.



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The Qmail Handbook
The qmail Handbook
ISBN: 1893115402
EAN: 2147483647
Year: 2001
Pages: 186
Authors: Dave Sill

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