Why did I receive a bounce message “Number of failed recipients exceeded. Come back in a few hours” while sending mail to clients hosted on your servers?
If you send email to multiple addresses hosted on our servers and 5 or more addresses are bad, you will receive a message back containing “Number of failed recipients exceeded. Come back in a few hours.” This feature is in place to prevent mass spammers from attempting what is called a Dictionary Attack. If the mail is legitimate, check the addresses you are sending to for correctness and try again later after the temporary ban is automatically lifted.
