We have two domains setup on our gwia to receive email. I setup a POP3 account in the client to be able to send email from our main address or the secondary. I used this article to setup the secondary address. It works for some and not for others and it appears to be a client issue. Certain users when they try get a Service Not Available error when trying to send email. I can login with their accounts on my machine and it works fine. I have uninstalled their client and reinstalled it again but it makes no difference. Any ideas on what else I can try?