once anyone subscribes to an issue queue, posting issues/followups is much slower

i haven't looked closely at the mail.inc code yet, but i'm pretty sure that all email subscription stuff is handled directly when you click "submit" for either an issue or followup. it appears to be done in a blocking way, such that you have to wait for the mail agent on your webserver to send the message out before the user gets the web page back that shows their post. i'm not sure if there's much we can do about this, but it's very noticeable on the site i'm setting up at my day job, and rather annoying.

it seems like it'd be nice to be able to send out email in the background. i don't know if there's any infrastructure (short of a cron hook, which would be way too large a grainularity for this) to do tasks in the background within drupal. i just wanted to post an issue here in case anyone has any bright ideas for if/how we can/should solve this. maybe it's just that our webserver is too slow (it's a pretty loaded machine, doing a lot of other things), and there's nothing we need/want to do to the drupal code to make it better. feel free to mark this as "won't fix". ;)

thanks,
-derek