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.