Emails from a particular user keeps bouncing


I have a user that is trying to send an email to a user in the company but the emails keeps bouncing with the error:

This message was rejected by the recipient email system. Please check the recipient's email address and try resending this message, or contact the recipient directly. For more tips to resolve this issue see DSN code 5.1.0 in Exchange Online. If the problem continues contact your help desk.

When I carryout message tracking I get the following:

SMTP: Message submitted to Advanced Queuing
SMTP: Started Message Submission to Advanced Queuing
SMTP: Message Submitted to Categorizer
SMTP: Message Categorized and Queued for Routing
SMTP: Non-Delivery Report (NDR) Generated

I can however receive the message if it is sent to the administrator email address.

They have a SBS 2003 setup with Exchange 2003.

They use Sophos Pure message for Anti-spam but have gone through this and cannot see anywhere that this email address could be blocked. I have added it to the safe senders list too.

There are no rules in outlook that could be blocking the either.

Is there anything else that I could check?

Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Andy MInternal Systems ManagerCommented:
What happens if they send an email to another user on the same domain? Does that bounceback at all?

If not (and it's just this one user they can't send to) it may be worth checking Outlook/Webmail's own safe senders/blocked senders lists as the sender's address/domain could be in there (seen it happen many times). I usually prefer to do this in webmail to ensure I'm seeing exactly what the server setup is.

You could also delete all rules for the recipient in Outlook open outlook with a /cleanrules switch in case there's an old/corrupted rule that hasn't deleted correctly causing it.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Rob ShinwellMessaging SMECommented:
Try sending an email via Telnet from your Exchange server to the recipients mail server. Your should see a rejection message If the recipients mail server is rejecting your email
granite03Author Commented:
They can receive our emails, its when they send to us that is the problem.

They can send to the administrator email address and it gets through without any problems but when sending to the user it is intended for it bounces back with the message above.
Rob ShinwellMessaging SMECommented:
Is this isolated to this one particular recipient. Try asking the 3rd party to send the same email to an alternative recipient to see if they get the same NDR.
Zacharia KurianAdministrator- Data Center & NetworkCommented:
it sounds like the user is using "cached email address".

I suggest to delete the cache address from this user. Then let this user select the address from global address list.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.