Email Error 554, Relay Access Denied

[dalek]

What about the recipients POP settings??? Also what about SMTP Authentication settings, on the users PC.

[AngelicKnight]

Confirmed it's not a user problem -- It's something with the Exchange server, as the problem is specific to users on this particular server, so I've discovered. It simply wont' allow relay to this account, though it will to every single other account.

One thing we discovered is that the domain that the email address belongs to does not resolve to an IP address, thus it has no A record. Could this be part of the problem?

[morganlefay]

One thing we discovered is that the domain that the email address belongs to does not resolve to an IP address, thus it has no A record. Could this be part of the problem?

Yes

Had this problem on one site with an exchange server...no reverse look up...certain domains will block this.

Work around is to upload mail to ISPs smtp server ....

MLF

[Nokia]

Yep it sure would AK!

As MLF says if it cant do a reverse lookup it could very well be bounced - this is how some Anti Spam filters work!