Outlook 2007 has intermittent Send problems

I installed a brand new SBS2008 (w/ Exchange2007) server into a client network that had no server before; they had been POPing their e-mail. I set up Exchange, and all PCs/users work just fine, except for ONE user gets messages rejected from their OWN server when he tries to send e-mail..Now, this only happens intermittently, but here's the error he receives:

"You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission."

Now, let me emphasize that he is NOT trying to send on behalf of another user, nor is he a delegate of another mailbox/account. Again, this will happen for several hours, and then the problem will go away altogether for 1-2 days, or whatever, then it will return.

BUT, when he uses OWA, he never has this issue, which led me to believe that his Outlook profile was corrupted. As you would expect, I trashed his OL2007 profile and created a new profile, and 1 day later, he had the EXACT same problem. Again, he is the only person having this problem, and ALL other mailboxes/Outlook accounts are behaving fine and get no errors. ONE other user had the same problem within 1 day of the guy still having issues today, but I built a new Outlook profile for him, and that guy hasn't had the problem since.

My client is frustrated, and *I* am frustrated, since I cannot find a damn solution to this quandary!

Can you please HELP!!

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There could be a windows profile issue. Please create a new windows profile for this user.

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ethernet69Author Commented:
Thanks for the feedback, but this is easier said than done. Why would I simply trash his Windows user profile first without trying other things first that are not so destructive...? backing up all the information and creating another user profile, then bringing it all back would be cumbersome, at best. Do you have any hard evidence that leads you to making this suggestion, or is it a guess?
ethernet69Author Commented:
Oh, and by the way, if it were a user profile issue, why is the problem intermittent?
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This not a guess. I am telling from my experiences. Creating new windowsd profile creates a new regsitry hive for the user. If you say that the issue is intermittent, then there could be some registry corruption or Outlook is waiting for soem information. A netmon trace can tell what exactly is happening.

ethernet69Author Commented:
Thank you, ashishkpandey. Please pardon my skepticism, but there are LOTS of jokers on EE who just throw a random "solution" over the transom. so, when it's a difficult-to-implement solution, then I will certainly want to know if this is a known problem. Please tell me more about the "netmon trace" that can tell me exactly what is happening before I rebuild the user profile.
ethernet69Author Commented:
I'm sorry, but sending me links to long articles on how to use the NetMon program is not terribly helpful. I was hoping you could offer more insight on exactly what needs to be done and what you are suggesting I can actually determine using Netmon.

Again.......taking netmon is different and reading it is different. You need to be specailised in .NET and TCP . You can take Netmon Traces....but who will analyze it?
ethernet69Author Commented:
While I was skeptical about this possible solution, it actually did work. It's never fun to have to comletely re-create a windows user profile, but I did it, and the Outlook client issue seems to have gone away. Thanks!
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