There is a limit of 500 emails per hour from one domain; mails sent over this limit will be dispatched back with an undeliverable error.
Most Happy@Net servers have a limit of 60 pop checks per hour for an e-mail address. If a customer exceeds this limit he’ll get a wrong password error message. To be automatically unlocked wait an hour. Disable auto checking or put a higher limit, for instance 10 minutes, to prevent it from happening again.
Mailing lists over 5000 require a semi dedicated or dedicated hosting solution. Dividing a large list into smaller ones to scrub round this limit is not allowed.
Mailing Lists Rules
1. No matter how large your e-mail list is anytime you send a message you have to throttle it.
Our recommendation is to send at least 1 email every 6 seconds. If your mailing list software doesn’t allow you to throttle you are to change it to something else. We recommend phplist that you can find in the control panel under fantastico. If the customer doesn’t throttle and tries to send for instance 500 emails the server will try to send all 500 massages in a second, which is impossible and will cause a server load to go high and server will be sluggish till the process is over. Any user causing the servers load going high will be suspended. A user that doesn’t throttle will be suspended for crashing the server.
2. To prevent high server loads mailing lists over 900 emails are allowed to be sent during off-peak times only. Off peak times are: all day Saturday and Sunday, and 1am - 8 am eastern time M-F.
3. Mailing to a mailing list you were given or purchased is considered to be spamming. Spam will result in termination of the offending account.
4. Any unwelcome e-mail sent will result in termination of the offending account. We take a zero tolerance stance against sending of unwelcome e-mail.
5. Any mailing list MUST meet the terms of all guidelines set forth by the United States.
These can be found at: http://www.ftc.gov/bcp/conline/pubs/buspubs/canspam.htm
6. Direct SMTP mailers are forbidden. Any mail should be relayed through the local MTA (localhost:25) for further delivery by the server and not done directly by scripts.