If you are exceeding 20 per minute, you risk being shut down. If you exceed 400 per hour (300 is suggested, for safety; 400 is the "drop dead" limit), you'll be shut down. Both limits apply. If you dump 100 emails into the "out bin" at once, you're going to be in trouble if it takes less than 5 minutes to process. You'll need to figure out a way to batch your mailings into smaller groups. Is there any way (perhaps by directly using phpMyAdmin) to export your user address list (as a CSV) to PHPlist?

All LP needs to do is to stop penalizing for large quantities of emails, and start doing something to help us all keep within reasonable limits. If they could come up with a per-account email queuing service, that would be fantastic. You would email batches of mail, using normal PHP, web, and SMTP mailing services, without worrying about how many per minute or hour, and instead of being immediately sent out, they would be held and doled out at 5 per minute or whatever. You could request a temporary higher rate, if you know that you have only a small number of emails (not enough to hit the 300/hr limit). A nice touch would be to assign priorities to mail, but that would involve changing the mailing interface (maybe a new header field?).

Doing this would eliminate the need for PHPlist's and SMF 2's email rate throttling, combine all the separate mailers you have to worry about (combined rate exceeding caps), and getting whacked for accidentally dumping too many emails into the "out box" at once. Storage for your personal outbound queue would count towards your disk space allocation. Obviously, there would have to be some "reasonable" limits as to how much outbound mail you could queue up (it would be unfair for someone to queue up a million emails at once) -- perhaps you could purchase additional space if you need it.

I'll submit this on the Feedback board too.

Well, the primary reason that they have limits so low in the first place is that they don't want their servers branded as sources of spam. Many email services are watching how many emails they get in a short time from a given IP address (and everyone on a shared server shares the same email IP address). Go past some limit and the other services declare your entire server to be a spammer. It's unfortunate, but that's what's happened with the Internet.

If I Ran The Circus^TM, I would impose postage on all emails so that it would be too expensive to spam, yet affordable for those who legitimately need to email. It would also induce PC owners to scan for spyware, etc. that has turned their PCs into email-spewing zombies. Nothing like getting a $3000 postage bill for the month from your ISP, is there, to focus your mind on cleaning up your PC or website? Before anyone complains about how unfair that would be to Grandma, everyone would have a monthly email cap set (revisable upon agreement with your ISP or web host) so that you wouldn't get a nasty surprise if your server or PC were hacked. Residential users might get a credit: first 30 emails a month are free.

LP has the internal capacity to allow much higher email rates. Just a few years ago, you could send 1000 per hour. I'm sure they could handle more than 20 per minute per account, but I don't know about several hundred. It's what happens outside of LP that they're worried about. Maybe the email services could be induced to show a little leniency by telling them how many users a host has on a server, and tripping the alarm on emails per user * number of users, rather than a flat number per server. Finally, if LP queued up outgoing mail, they could take measures to distribute it evenly ("one to gmail, one to hotmail, one to yahoo, one to...") rather than dumping a whole bunch on one service at once.