sendmail, 4th Edition

The DialDelay option (DialDelay), if set, allows sendmail to try to connect a second time if the first connection attempt times out or fails. This option is intended primarily for dial-up connections, but it can also be useful if your fast connection is very busy.

Prior to V8.12, setting the DialDelay option caused it to be used by all delivery agents , even those for which it made little sense. Beginning with V8.12, the DialDelay option only affects delivery agents that have this F=Z delivery agent flag set.

You can add this to a delivery agent with the MODIFY_MAILER_FLAGS mc configuration macro:

MODIFY_MAILER_FLAGS(`SMTP', `+Z') this must be MAILER(`smtp') before this

Here, we add the F=Z delivery agent flag to the smtp delivery agent. As with all modifications of delivery agent flags, the modification must precede the MAILER declaration of the delivery agent.