Anyone any clue on this one? I have a mailbox that is supposed to auto reply ("thank you for your email we will respond in nnn days") to *** only *** external mail and NOT to internal mail. This auto reply rule (which is NOT a vacation rule...) works randomly, regardless of the original external sender. In other words, and as an example: external sends a mail and gets an auto reply the first time. For subsequent mails, he MAY receive an auto reply, and MAYBE he will not. GWCHECK shows absolutely nothing in particular.

This is how the rule is constructed: apply rule to items where type is email AND from does not contain (internal domain name) OR from does not contain NAME_OF_GWPO OR from does not contain NAME_OF_GWSYSTEM AND from contains @.

Printscreen partially obfuscated:

Click image for larger version. 

Name:	auto reply rule.PNG 
Views:	8 
Size:	17.7 KB 
ID:	5792

Thanks anyone for any clue ;-)