My outgoing emails are stuck in my smtp queue because of 453 4.1.1 TT501 and TT502 errors. I thought that "time" would clear this up. The cause is certainly an email I sent to our church members which likely exceeded the recipients limit. But that was Monday, and we are now Wednesday. Doesn't the limit reset after a while?
Looks like you know exactly what the problem is. Too many recipients and that both the hourly limit counter (TT501) and the daily limit counter (TT502) have been exceeded.
If no more mail messages are sent then the counters will be fully reset in 24 hours. But if your email client has queued mail messages in the outbox for automatic retrys then every time the counter goes up to allow more mail messages out so the sending limit is tripped and the cycle repeats.
The fix is to go offline and to delete the waiting mail messages in the outbox. Then wait for the counters to be fully reset and you'll be good to go.
The normal limit is 50 recipients per hour or 500 per 24 hours. Best to break up group sending to no more than 50 recipients in any one group. And then to stagger group sending throughout any one day.
The smaller the group the better. This is because one failure of one email address to get through can stop the sending of the whole group that then starts a retry of the whole group and the send count can then rapidly increase. Keep an eye out for mailboxes rejecting your email or email bouncing back as undeliverable and remove those addresses from the group sends.
Other than the above advice, for most mail users, the advice to 'try again later' works. If a mailbox has been compromised and used to send unauthorised mail that's tripped the counters (it's the main reason the counters exist) then that's an urgent password change requirement.