A client of ours was running an in-house Exchange server and decided to move to Office 365... To facilitate the cutover migration, we needed to install a temporary SSL certificate on the server which we bought for a period of three months. We have completed the migration and all of the mailboxes are in the cloud. 

BUT, the certificate has just expired, and when I needed to connect a new Outlook 2013 client to the Office 365 account it comes up with an error saying that the certificate has expired... I've tried to manually set up the account also, but it wont accept the ExchangeID I get when I connect to powershell and run the Get-Mailbox command. It says the server does not exist. 

What is crazy is that if I set up Outlook with very same account from my site (as a test), which has no SSL cert at all, it connects seamlessly. Can anybody give me advice on what approach I might take to resolving this? 

• Edited by JonathanAnon Wednesday, February 18, 2015 11:49 PM

Okay, I managed to get this sorted myself with a waste of two days. I reinstalled the PC after the other engineer on the job had tried everything else..then bought a certificate, which sorted out the certificate error on the PC, but it still wouldnt connect. 

I downloaded the Microsoft Connectivity Analyzer tool (the offline one not the online one) and ran this from the PC. It failed on the autodiscover... On the PC when I ran a nslookup autodiscover.domain.com it found all the records fine. I downloaded WireShark and tried to pinpoint where in the communication the issue was, but it was amgibuous. I compared it to a good connection from my own PC and I could see where it was breaking down with a RST ACK when I was expecting a SYN ACK, but with no particular reason. 

Finally, I tried to connect to http://autodiscover.domain.com/autodiscover/autodiscover.xml on the PC, but Google Chrome kept timing out with no error. When I opened this same address in IE, it told me that there was an issue with the firewall... So I turned off the content filter on the firewall, a Zywall USG-20, and the PC connected first time. 

hope this helps somebody else.