Just implemented IPs over the weekend and we have some groups we don't want to send un-reviewed attachments. On our older, perhaps crappier email filtering devices, things like meeting requests from outlook would flow through as non-attachments. Responses to them would show up as attachments though.
Is there a quick fix to allow these through (but catching ones that have actual attachments)?
Yes, invitations are attachments. They have a content type of "text/calendar" (sorry kluu, "meeting.ics" is the file name, not the content type). You can use the "attachment-mimetype" filter rule to detect them, but this rule returns true if any attachment is of this type. A message might have both a "text/calendar" attachment and then something else you don't want to get through. There doesn't seem to be any easy way around this. There is a "drop-attachments-by-mimetype" filter action, but it only lets you list the attachment types to drop. You can't say "drop all attachments except this type".
Incidentally, it is my experience that you shouldn't depend on the "meeting.ics" file name. Our Exchange installation quit putting file names on text/calendar attachments when we upgraded to Exchange 2007. I don't know if this is due to a change in Exchange or a change in our configuration, but in either case "meeting.ics" doesn't appear to be reliable. The "text/calendar" content type is.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...