SMM:08-28
Sendmail Installation and Operation Guide
RFC 2821 section 4.5.3.2 (or RFC 1123 section 5.3.2) are:
connect
The time to wait for an SMTP connection to open (the connect(2) system call)
[0, unspecified]. If zero, uses the kernel default. In no case can this option
extend the timeout longer than the kernel provides, but it can shorten it. This
is to get around kernels that provide an absurdly long connection timeout (90
minutes in one case).
iconnect The same
as connect, except it applies only to the initial attempt to connect to
a host for a given message [0, unspecified]. The concept is that this should be
very short (a few seconds); hosts that are well connected and responsive will
thus be serviced immediately. Hosts that are slow will not hold up other deliv-
eries in the initial delivery attempt.
aconnect
[0, unspecified] The overall timeout waiting for all connection for a single
delivery attempt to succeed. If 0, no overall limit is applied. This can be used
to restrict the total amount of time trying to connect to a long list of host that
could accept an e-mail for the recipient. This timeout does not apply to Fall-
backMXhost
, i.e., if the time is exhausted, the FallbackMXhost is tried next.
initial
The wait for the initial 220 greeting message [5m, 5m].
helo
The wait for a reply from a HELO or EHLO command [5m, unspecified].
This may require a host name lookup, so five minutes is probably a reasonable
minimum.
mail
The wait for a reply from a MAIL command [10m, 5m].
rcpt
The wait for a reply from a RCPT command [1h, 5m]. This should be long
because it could be pointing at a list that takes a long time to expand (see
below).
datainit
The wait for a reply from a DAT A command [5m, 2m].
datablock
The wait for reading a data block (that is, the body of the message). [1h, 3m].
This should be long because it also applies to programs piping input to send-
mail which have no guarantee of promptness.
datafinal
The wait for a reply from the dot terminating a message. [1h, 10m]. If this is
shorter than the time actually needed for the receiver to deliver the message,
duplicates will be generated. This is discussed in RFC 1047.
rset
The wait for a reply from a RSET command [5m, unspecified].
quit
The wait for a reply from a QUIT command [2m, unspecified].
misc
The wait for a reply from miscellaneous (but short) commands such as NOOP
(no-operation) and VERB (go into verbose mode). [2m, unspecified].
command
In server SMTP, the time to wait for another command. [1h, 5m].
ident
The timeout waiting for a reply to an IDENT query [5s
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, unspecified].
lhlo
The wait for a reply to an LMTP LHLO command [2m, unspecified].
auth
The timeout for a reply in an SMTP AUTH dialogue [10m, unspecified].
starttls
The timeout for a reply to an SMTP STARTTLS command and the TLS hand-
shake [1h, unspecified].
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On some systems the default is zero to turn the protocol off entirely.