MS Exchange 2007 Receiving Error 550 5.4.4 ROUTING.NoNextHop; unable to route from one user

We have client that is running MS Exchange 2007. There are other users that can e-mail to However when one user e-mails to this address he receives the following error:

Diagnostic information for administrators:

Generating server: server.domain.LOCAL

#550 5.4.4 ROUTING.NoNextHop; unable to route ##
All users are using MS Outlook to access their Exchange mailbox to send the e-mails. Any help or direction to look would be greatly appreciated.

Thanks in advance.

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DovinshkaConnect With a Mentor Commented:
" The SMTP server is setup in MS Exchange not the local client. "

In Exchange, a user can have multiple email accounts. The default account is highlighted and the word SMTP is in capital letters. Check to see what email address is set as the default.

Try sending an email by directly typing the email address and not using the outlook contact.

Is this particular user using the auto-completed entry in Outlook? i.e. are they typig us...and the email address is selected automatically for them?

Does the user have their default SMTP address set correctly? domain.local will not resolve externally.

jenkinsmeAuthor Commented:
The user is getting the address from their Outlook Address book and inserting it into the e-mail that way.  The SMTP server is setup in MS Exchange not the local client.
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jenkinsmeAuthor Commented:
Thank you for pointing me in the right direction. The user was able to e-mail to that address by typing in the e-mail address which means that somewhere in his contact list he has incorrectly entered the users e-mail address.
Thank You for your quick response and help.
Glad to have helped :)
Helped me too, dud cache was the issue.
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