I'm on 000webhost and I use Mark Jaquith's "Subscribe to Comments" among others and my hosting account was suspended last night when a discussion, well, got out of hand.
000webhost's email sending limit is 'No more than 30 emails per 5 minutes and no more than 100 emails per hour.'
000webhost's PHP config doesn't support SSL/TLS so I can't send via Gmail. In any case, Gmail also has a limit of "100 people at a time".
So as a stopgap I added a "ORDER BY comment_date DESC LIMIT 28" clause to Jaquith's plugin and crossed my fingers.
Before I go study how to add the Throttle plugin to Swift Mailer and use Swift as a wp_mail() replacement, I thought of coming here to ask if someone has already made a throttling solution or plugin.
Or maybe someone knows a free or low-cost SMTP server service?