To limit the amount of time a
message can remain in the queue before being bounced,
sendmail must know when that message was first
placed in the queue. That time of first placement is stored in the
T line in the qf file. For
example, the following number represents the date and time in seconds
since January 1, 1970:
T703531020
Each time sendmail
fails to deliver a message from the queue, it checks to see whether
too much time has passed. It adds the T line value
to the value specified in the Timeout.queuereturn
option (Timeout). If that sum is greater than
the current time, the message is bounced instead of being left in the
queue.
Messages are occasionally left in the queue for longer than the
normal timeout period. This might happen, for example, if a remote
machine is down but you know that it will eventually be brought back
up. There are two ways to lengthen the amount of time a message can
remain in the queue.
The preferred way is to create a temporary separate queue directory
and move the necessary queued file to that temporary holding place.
When the remote site comes back up, you can later process the files
in that other queue by running sendmail with an
artificially long Timeout.queuereturn value (Section 11.9).
A second way to extend the life of messages in the queue is to edit
the qf file and change the value stored in the
T line. Just add 86400 to that value for each day
you want to extend. Care is required to avoid editing a file that is
currently being processed by sendmail.
There is currently no plan to give sendmail the
ability to rejuvenate queued messages (make old messages appear
young).
The form of the T line in the
qf file is:
Tsecs
The T begins the line, and the
secs must immediately follow with no
intervening space. The numeric text that forms
secs is converted to an integer using the
C-library routine atol(3). That routine allows
secs to be represented in text as a signed
decimal number, an octal number, or a hexadecimal number.
If secs is absent or the entire
T line is absent, the time value is zero. A zero
value causes the mail message to time out immediately.
There should be only one T line in any
qf file. Multiple T lines cause
all but the last to be ignored.
