1. Obscenities such as multimegabyte-long To fields. If each To address is
processed somehow and the processing takes a 0.01 second, that's a limit of
only 60,000 addresses in To.
To some extent this is a quality of implementation matter. The server has
a clear time budget for whatever processing it wants to do, so it ought to
have a sensible way of coping with running out of time.
I'd think that the chances of a message with 60,000 addresses in the To:
line being of interest to the people to whom it was sent would be vanishingly
small, so if the MTA screws up and loses it, that would be a sensible
But I agree it would be nice to do that in less than 10 minutes.
As I hardly need tell people here, if you make stuff more idiot proof,
you'll meet more ingenious idiots. I'm wondering how many of the over
10 minute messages were a) of interest to the people they were sent to
and b) couldn't have been worked around reasonably easily.