MAPI and IPv6

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Duncan Smith noted recently that MAPI appears to have a problem with IPv6. He contacted me to see if I knew anything about the issue. I didn't, but one of the Exchange PMs spotted the connection between Duncan's issue and the recently reported DSProxy issue over on the Ehlo blog. It turns out that issue affects regular MAPI connections - not just RPC/HTTP.

The gist is - right now, DSProxy doesn't listen on IPv6. It only listens on IPv4. So if you're running a MAPI client on an IPv6 enabled box (such as, say, installing the MAPI download on an IPv6 enabled Exchange 2007 server), then profile creation is going to fail when the client tries to ask the server for a referral to a GC.

As the Ehlo article notes, a fix is in the works. Until then, you can try one of the following:

  • Turn off IPv6 on your server - Ehlo gives instructions for that - this has been confirmed to work .
  • When creating a MAPI profile, instead of using the Exchange server name, use the name of a GC or DC. We've not had a chance to test this yet - we'd love to hear if someone tried it and it worked.