Normally this error occurs when a user isn't authorized to send through the Smile mail servers. In most cases, just checking your mail first will authorize you to send mail. Most email programs check mail before sending when they start up, but in some cases, if the program opened, and mail wasn't checked, you can receive a bounce message with the following error:
553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
This applies to sending mail to other users outside of Smile's network. If people outside Smile Global are receiving this error when sending mail to you, please submit a support ticket.
