Queue Interval

The q flag defines how often sendmail runs the queue. If you run in mode i or b (the default), this time can be relatively long, because it is only relevant when a host that was down restarts. If, however, you run in q mode, the time should be relatively short, as the flag defines the maximum amount of time that a message may sit in the queue. Typical queue time is set to between 15 minutes (q15m) and 1 hour (q1h).