Hi, Our Exchange server rebooted overnight, upon connection to Exchange in the morning, some clients are popping up User Certificate windows when connecting to Exchange, this comes up over and over again and we never get anywhere. No configuration we know of has changed, it is quite strange, testing the autoconfiguration stuff all looks good from a PC that is working. Anyone know where I can start looking? No certificates have expires, OWA and OA seems to work fine as well, this is an issue occuring when internal machines on the domain cannot connect to Exchange. Thanks, Terry

You need to look at the certificate to see where it is coming from. That would give you a clue. Most likely those clients had Outlook running and autodiscover has gone through its process to find the server. It is probably looking at a server outside of your network. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources

Hi Simon, It is coming from the FQDN of our ISA server which does all the OA/OWA proxying, which is exchange.domain.com. This can be rectified by turning off the Outlook Anywhere option for internal users, but I am wondering why this has all of a sudden popped up? When I do the remote connectivity analyzer for AutoDiscover it works fine... Any ideas? Regards, Terry

The server was down, the client switched over to use the Outlook Anywhere configuration, which is pushed out to all clients when you configure Outlook Anywhere as part of autodiscover. It was able to connect to the host which is your ISA server. Restarting the Outlook clients should stop it from popping up. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources

That is what I thought (and usually happens) - although the certificate popup continues to come, I have no idea why... I don't know why Outlook would prompt for a client certificate anyway when OA is using Basic auth and ISA doesn't request a client cert... We have scheduled downtime on our Exchange server before and this has never occured... strange one...

From what I can tell, it seems to be only Outlook 2003 users...

On Mon, 11 Oct 2010 23:07:12 +0000, Tabmow wrote: >Our Exchange server rebooted overnight, upon connection to Exchange in the morning, some clients are popping up User Certificate windows when connecting to Exchange, this comes up over and over again and we never get anywhere. No configuration we know of has changed, it is quite strange, testing the autoconfiguration stuff all looks good from a PC that is working. > >Anyone know where I can start looking? No certificates have expires, OWA and OA seems to work fine as well, this is an issue occuring when internal machines on the domain cannot connect to Exchange. If I'm understanding the problem (which doesn't appear to be a warning that the certificate has expired, that the issuer is untrusted, or that the server name and certificate name don't match), try this: Check each of the IIS virtual directories. On the "Directory Security" tab, click the "Edit..." button in the "Secure communications" area. If the "accpt..." or "require..." radio button is selected in the "Client certificates" area, select the "ignore..." radio button. --- Rich Matheisen MCSE+I, Exchange MVP --- Rich Matheisen MCSE+I, Exchange MVP

Hi, How did the problematic Outlook 2003 clients connect with the Exchange server? HTTPS or RPC? Thanks AllenAllen Song