NAME

qmail-smtpd - receive mail via SMTP

SYNOPSIS

qmail-smtpd

DESCRIPTION

qmail-smtpd receives mail messages via the Simple Mail Transfer Protocol (SMTP) and invokes qmail-queue to deposit them into the outgoing queue. qmail-smtpd must be supplied several environment variables; see tcp-environ(5).

If the environment variable SMTPS is non-empty, qmail-smtpd starts a TLS session (to support the deprecated SMTPS protocol, normally on port 465). Otherwise, qmail-smtpd offers the STARTTLS extension to ESMTP.

qmail-smtpd is responsible for counting hops. It rejects any message with 100 or more Received or Delivered-To header fields.

qmail-smtpd supports ESMTP, including the 8BITMIME and PIPELINING options.

TRANSPARENCY

qmail-smtpd converts the SMTP newline convention into the UNIX newline convention by converting CR LF into LF. It returns a temporary error and drops the connection on bare LFs; see http://pobox.com/~djb/docs/smtplf.html.

qmail-smtpd accepts messages that contain long lines or non-ASCII characters, even though such messages violate the SMTP protocol.

CONTROL FILES

badmailfrom

Unacceptable envelope sender addresses. qmail-smtpd will reject every recipient address for a message if the envelope sender address is listed in badmailfrom. A line in badmailfrom may be of the form @host, meaning every address at host.

clientca.pem

A list of Certifying Authority (CA) certificates that are used to verify the client-presented certificates during a TLS-encrypted session.

clientcrl.pem

A list of Certificate Revocation Lists (CRLs). If present it should contain the CRLs of the CAs in clientca.pem and client certs will be checked for revocation.

databytes

Maximum number of bytes allowed in a message, or 0 for no limit. Default: 0. If a message exceeds this limit, qmail-smtpd returns a permanent error code to the client; in contrast, if the disk is full or qmail-smtpd hits a resource limit, qmail-smtpd returns a temporary error code.

databytes counts bytes as stored on disk, not as transmitted through the network. It does not count the qmail-smtpd Received line, the qmail-queue Received line, or the envelope.

If the environment variable DATABYTES is set, it overrides databytes.

dh2048.pem

If these 2048 bit DH parameters are provided, qmail-smtpd will use them for TLS sessions instead of generating one on-the-fly (which is very timeconsuming).

localiphost

Replacement host name for local IP addresses. Default: me, if that is supplied. qmail-smtpd is responsible for recognizing dotted-decimal addresses for the current host. When it sees a recipient address of the form box@[d.d.d.d], where d.d.d.d is a local IP address, it replaces [d.d.d.d] with localiphost. This is done before rcpthosts.

morercpthosts

Extra allowed RCPT domains. If rcpthosts and morercpthosts both exist, morercpthosts is effectively appended to rcpthosts.

You must run qmail-newmrh whenever morercpthosts changes.

Rule of thumb for large sites: Put your 50 most commonly used domains into rcpthosts, and the rest into morercpthosts.

rcpthosts

Allowed RCPT domains. If rcpthosts is supplied, qmail-smtpd will reject any envelope recipient address with a domain not listed in rcpthosts.

Exception: If the environment variable RELAYCLIENT is set, qmail-smtpd will ignore rcpthosts, and will append the value of RELAYCLIENT to each incoming recipient address.

rcpthosts may include wildcards:

   heaven.af.mil


   .heaven.af.mil
    

Envelope recipient addresses without @ signs are always allowed through.

rsa2048.pem

If this 2048 bit RSA key is provided, qmail-smtpd will use it for TLS sessions instead of generating one on-the-fly.

servercert.pem

SSL certificate to be presented to clients in TLS-encrypted sessions. Should contain both the certificate and the private key. Certifying Authority (CA) and intermediate certificates can be added at the end of the file.

smtpgreeting

SMTP greeting message. Default: me, if that is supplied; otherwise qmail-smtpd will refuse to run. The first word of smtpgreeting should be the current host's name.

timeoutsmtpd

Number of seconds qmail-smtpd will wait for each new buffer of data from the remote SMTP client. Default: 1200.

tlsclients

A list of email addresses. When relay rules would reject an incoming message, qmail-smtpd can allow it if the client presents a certificate that can be verified against the CA list in clientca.pem and the certificate email address is in tlsclients.

tlsserverciphers

A set of OpenSSL cipher strings. Multiple ciphers contained in a string should be separated by a colon. If the environment variable TLSCIPHERS is set to such a string, it takes precedence.

SEE ALSO

tcp-env(1), tcp-environ(5), qmail-control(5), qmail-inject(8), qmail-newmrh(8), qmail-queue(8), qmail-remote(8)