I'm using outlook 2007.
If I mail to a certain e-mail address and I click on "send", I instantly receive an email saying that the mail send didn't reach the recipients.
With the following error:
'firstname.lastname@example.org' op 5-2-2010 15:47
550 "Unknown User"
It only seems to happen on my outlook address, if I use my hotmail or gmail (both webmail) then everything works fine.
The email@example.com can mail me, that works fine. If its used to mail me on my outlook address and I reply the same thing happens, I get the 550 error.
If I check the email properties, the headers box is completely empty. It seems that the email doesn't even reach my SMTP server.
I can't remember where, but I read somewhere that you can "empty" the outlook cache to solve problems like this, now I searched Google and I figured out how to clear the "Download Cache temp folder" and the "Email Address Auto Complete Cache" but those aren't things I'm looking for.