At present you can enable the mail queue and set a maximum number of emails per minute, I would like to see an option to set a maximum per hour as most hosts limit email relays on an hourly basis and not per minute.
Also it would be nice to see a stat that is done on an hour basis from the top of the last hour so say it's 13:30 and I've sent 10 emails since 13:00 and I have a maximum of 100 emails an hour, the stat would show something along the lines of:
QuoteEmail Usage in past hour (from top of hour just passed): 10/100
---------------------
Also if there is an hourly limit sent on email say I have it set as 100, it would be nice to reserve a certain percentage or number of these emails for registration emails of new users.
In case the admin sends out a email to the all members and there is 500+ the registration email wont be sent until all those emails are sent so your looking at at least 5 hours till the new user gets their registration email and if they have to validate via email they will be waiting 5+ hours and might just give up on the forum in question.
Just a few thoughts.