Mac Outlook 2011 Error 18500

My client is running SBS 2011/Exchange 2010.  He is running on a Mac with Outlook 2011

The mac is able to RECEIVE email just fine from the exchange server.
However, the Mac CANNOT SEND any email.  Just sending a short 1 word email, with no attachment, gives the error:

"HTTP error. The server cannot fulfill the request.
Mail could not be sent. The message has been moved to your Drafts folder.
Error -18500"

I *really* hope someone can help!  I''m stumped.

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Tony JohncockLead Technical ArchitectCommented:
Yeah this can be a fairly common problem.

I found I had to enable basic authentication on the EWS subfolder of the Exchange box's IIS manager to get Outlook 2011 to behave properly.

If you make this change, remember to issue an IISRESET on the Exchange server otherwise it won't take until reboot.
jgutmanAuthor Commented:
Big Point:  This happens on *tiny* emails also, as well as emails without attachments.  That's the point I don't understand.  Everything I've read so far about this error is with attachments or big emails.

EWS is enabled and Basic authentication is turned on.  Couldn't get Outlook to connect to Exchange without doing this.

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Tony JohncockLead Technical ArchitectCommented:
Crikey it looks like you're far from alone:

From what people are saying, it appears to be a regressional bug that's found it's way back into Outlook 2011..
jgutmanAuthor Commented: no real solution yet...

Anyone else??
I have a same error with  SBS 2008 and outlook 2011 any solution??
jgutmanAuthor Commented:
Hi Salasl:

Nope....  :(

ok, I continue to seek a solution
jgutmanAuthor Commented:
Please do let me know if you find one!  I'm actually consitdering calling microsoft and paying for a support call to solve the issue.....but I'd rather not   :)
I solved the problem. Upgrade Exchange to sp3 and install the latest release.
jgutmanAuthor Commented:
Closing question for now

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jgutmanAuthor Commented:
No solution so far
I have the same problem, is this solved yet ?
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