Sendmail can be asked to queue (but not deliver) mail if the system load average gets too high using the QueueLA ( x) option. When the load average exceeds the value of the QueueLA option, the delivery mode is set to q (queue only) if the QueueFactor ( q) option divided by the difference in the current load average and the QueueLA option plus one exceeds the priority of the message -- that is, the message is queued iff:
pri > { bold QueueFactor } over { LA - { bold QueueLA } + 1 }
The
QueueFactor option defaults to 600000,
so each point of load average is worth 600000
priority points
(as described above).
For drastic cases, the RefuseLA ( X) option defines a load average at which sendmail will refuse to accept network connections. Locally generated mail (including incoming UUCP mail) is still accepted.