If sendmail normally waited any significant time for such things then
the whole of the internet's E-Mail would instantly grind to a halt I
think. I think you need to sort out this sendmail slowness (if that's
what it really is), it definitely shouldn't be that way and lots of
other things would break as a consequence if it is really slow.
Hmm. I'm currently googling on DNS lookup delay in comp.mail.sendmail,
and this seems to be a recurring issue.
I suspect things *are* normally that way, it's just that the delays on
each mail occur in parallel, and so don't particularly hold up normal
processing.
I'm not going to be much help on fixing sendmail for you I'm afraid
though.
Alas. Well, I think I may have found a solution. Certainly the delay on
sendmail has gone away: I wait to see if it is still working...
In case anybody else gets stuck on this problem, here is the solution (as
a fix to sendmail) that I have adopted. Edit sendmail.mc (or whatever,
depending on how your installation work; in my case, I edit `hostname`.mc)
and add the following line:
define(`confDELIVERY_MODE',`defer')dnl
and reconfigure/restart sendmail.
This configuration setting configures sendmail to accept all mail
immediately and not perform DNS until "the actual queue run" (whatever
that is).
I have to confess I'm not yet happy: `mailq` now reports 59 requests
in my mail queue, and they seem to just be sitting there. Reading about a
bit it seems that I have to wait for the next queue run, which only
happens every 30 minutes.
Not so happy about this: now I have to delay my incoming mail by up to 30
minutes. I'll try tweaking the queue time, but this seems very
unsatisfactory.