Hopefully someone more clued up on this than I will be able to point me in the right direction. As I'm a little stumped..
I'm having an odd issue with a customers e-mail which only happens with one specific domain name, and only on Xtra. Everything works fine, except for when Xtra customers attempt to e-mail them.. if the mail is sent via the Xtra SMTP servers then it gets rejected instantly (as soon as the RCPT is issued) as a 'Invalid Recipient'. This happens with all accounts @ that domain, and I have verified that the accounts exist and that the MX records are set correctly.
I'm told when the domain name was originally registered is was registered & hosted by Xtra (but since moved away). Now, the rejection comes back so instantly that I'm wondering if it's possible they still think they're hosting it internally or something?
Any thoughts on where I should look / who I should be talking with next?