- - Microsoft
- -- (deprecated) Microsoft Windows OS (XP/NT/Vista)
- ---- 550 "Unknown User"
tangor - 11:31 am on Feb 15, 2010 (gmt 0)
I have a client with similar problems under Outlook.
Vanished when I installed Thunderbird and suggested he try that for a day or two.
Don't know why the problem exists, just know that there is at least one solution.
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