Sending as a different email address via talktalk

I'm trying to help a talktalk user to set up the ability to send emails from a different domain.

On Plusnet I'm forwarding emails for [email protected] to his TalkTalk email address - that's working fine.

I've just talked him through setting up a second account in OE with the intention of him being able to reply to/send emails as [email protected] (or as his normal email address for emails which are nothing to do with ourdomain.org.uk). However when he tries to send the email is rejected because of an invalid senders address.

Is there a way you can validate an email address on TalkTalk as you can on Google?

What SMTP server is he using for that 2nd a/c for [email protected] ? It should be TT's SMTP and not that of his mail provider.

Shouldn't need to validate the address. Is he using smtp.talktalk.net as the SMTP server in both accounts? Google is different in that the servers are not linked to an ISP. Whereas, in theory, only TalkTalk users can connect to smtp.talktalk.net, and AFAIK this is based on the senders IP address rather than the senders e-mail address. That said, I don't normally use OE, or indeed TT e-mail at all (I use Gmail for my domain via Google Apps), but I did just now send mail via smtp.talktalk.net even though the sending e-mail address is not a TT one.

Where is the error coming from - the TT mail server or the destination? If the latter, then it may be checking SPF records for ourdomain.org.uk and bouncing the message back, depending on the destination server. The headers will confirm that.

The new account was set up using smtp.talktalk.net and the error came from there (the message didn't send).

One possibility: we copied all the settings across from his existing OE account - all the authentication was turned off. I'm wondering if it will only allow sending using a none TalkTalk email address if authentication is turned on, is this a possibility?

Edit: What would it do if the domain has no SPF records?

Edited by jelv (Wed 16-Feb-11 09:32:26)

Authentication should be switched off for the outgoing mail server - it is not used. Usage of smtp.talktalk.net is restricted to TT connections only, filtered by IP address, hence why authentication is not used. I just tried with OE and had no trouble sending mail via smtp.talktalk.net with a non-TT sender address. Has he tried testing it by sending a message directly to his @talktalk.net address using the smtp.talktalk.net account (which I presuming he is selecting in the "From" field when creating the message)?

If the domain has no SPF record at all, then everything should be fine. If it's smtp.talktalk.net that is rejecting the message, then probably SPF is not involved anyway.

The only other thing that springs to mind is virus checkers - if he has one that monitors outgoing mail, the configuration may need to be adjusted.