Hi All, We have an SBS2003 environment. I have multiple domains set up and all arriving to the Exchange without issue; I was asked to change the default sending address from @ADDRESS1.co.uk to @ADDRESS2.co.uk. They were able to receive to @ADDRESS2.co.uk and they can still receive to all their addresses. Problem is with sending. When we have @ADDRESS2.co.uk as the sending address, we receive "SMTP 550 Not Permitted". When we change the sending address back to @ADDERESS1.co.uk, sending resumes. All advice appreciated.

Hello, is there a gateway / smarthost / isp in front of that only accepts messages send from "@address1.co.uk"? Can you please check this? Hth.Regards Robert Genes

Hi Rob, The email was being routed through the smart host mail.btconnect.com. I removed this and punted back through DNS instead, this resolved the issue. Do you think I'll just need to wait a timeout period before routing back through mail.btconnect.com? Solution was to remove the smart host.

Hi Rob, The email was being routed through the smart host mail.btconnect.com. I removed this and punted back through DNS instead, this resolved the issue. Do you think I'll just need to wait a timeout period before routing back through mail.btconnect.com? Solution was to remove the smart host. To use BT's smart host you need to tell them what the domain is. Therefore you will need to contact them and then wait. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

I'm on the phone with BT as I type :-D