@EileenTwrote:
But if it is an address, why does the Failure notification say that this user doesn't have an account?
Hi, welcome to the forums.
The bty address is an internal handoff system address, not really a proper email address. I believe they were created when Yahoo took over the mail systems (and still have approximately half of the accounts - a guess), to handle some form of internal movement. These addresses were almost certainly set to be false addresses in the Yahoo mail database, and hence not mailable.
As you're probably aware, spammers use all sorts of "From" addresses, many of them fake or simply do not exist.
The problem with this current scenario, is that using the "internal" address as the "From" address will work to send emails, but no-one can reply - or at least get a non delivery.
As I said elsewhere, it's going to cause big issues.
With webmail user, it's possible to reset the default email address - Settings/Writing email - and choose the correct one from there. Also you might need to check the Name in the Settings/Accounts - to make sure when you're sending from the correct address, it has the name you choose. That item may have been altered as well.
This won't affect client/app users - apart from apparently Yahoo app users.
I personally believe that there won't be a "return to previous" setting for Yahoo, so this could be an ongoing issue for quite a while. Most people will have a btinternet.com as well as a btopenworld.com alias set in the webmail Settings. So it's likely that any reversal might pick the wrong address that people are used to.
