Time before giving up
When delivery of a message fails for some temporary reason (such as the destination server being down), sendmail will keep the email in its queue for the amount of time specified by this option, retrying delivery occasionally. Once the time limit is reached, a bounce message will be sent back to the sender and the message discarded.
This time must be given as a number followed by a character for the units, such asÂ 30m orÂ 1d. Valid units areÂ s = seconds,Â m = minutes,Â h = hours,Â d = days andÂ w = weeks.