[Wylug-discuss] Yahoo Mail sending mail incorrectly?

[gARetH baBB]

On Tue, 5 Oct 2004, Martyn Ranyard wrote:

> This works really well (when I remember to add the domain names to
> relay_domains in postfix on the backup mx server - grin).  Apart from yahoo,
> which contacts the primary mail server (halifax), but with a very wierd RCPT
> TO: command.  The email address it says it has email for is
> user at hosting.bluefedora.co.uk - The only way I can think of it coming up with

It's a CNAME problem.

Some MTAs will rewrite addresses if the address given points to a CNAME
(sendmail is common in doing this, but it's not that rare a rule).

Your post didn't say, but I googled for an example and saw that

"A @ .... # IP of webserver (so http://domain.name works as well as www)"

is actually a CNAME.

You have to make sure the "root" domain isn't a CNAME but has proper MX
and A records.