I have five desktops with XP Pro (with 10 users on each machine), 15 laptops with Win98 and one server with SBS 2000.
Everyone has one internal e-mail account, like firstname.lastname@example.org, and an external, like email@example.com. Exchange doesn't relay POP or SMTP because users need to access mail from several places, so they only collect mail from time to time.
The problem is that one single user on one single machine receives the following error every time he tries to send e-mail from Outlook XP using the external e-mail account: "553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)"
What can I do?
I may be wrong, but I am pretty sure that error is coming from a Qmail system. Even if it's not Qmail, it's definitely not an Exchange (or for that matter Small Business Server) error message. You'll need to contact the intended recipient of the message. It is their mail system (again, likely running Qmail) that is rejecting the message.
Feedback from original questioner:
Hi, Scott. There is an important detail that I didn't make quite clear: This user that has a problem sending e-mail can send messages successfully using any other PC, to the same recipients. As a matter of fact, when the problem occurs the message is rejected by the server (SBS on the company). I can't figure out why does it happens only with THAT user on THAT machine. Thanks for your help.
The reason it only happens for that user on that machine is likely because that one machine is misconfigured. It sounds like it is set to use some other account settings and isn't sending the e-mail to the proper SMTP server. I would double-check the e-mail account settings on this system against one of the working systems. I would be very surprised if they were both configured identically. If they are, you might consider deleting and creating a new mail profile for this user on the non-working machine.