Hi folks,

I get a strange bounce message when I try to email or respond to emails from one of my clients:

The mail system

<Xxxxxxx@water-doctor.com>: host mail.water-doctor.com[] said: 553
sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)

Why is the remote mail server telling me this? I'm not trying to relay off that server, just send mail to it. Is this a misconfigured server on their end?