Research this issue for 4 days and I'm still not sure how to fix it. I have two exchange 2010 servers in my environment and I recently deploy new exchange 2013 server. I moved my inbox to the new server and everything is working fine. I'm able to send and receive emails internally and externally as well as accessing OWA. But on my android phone I'm getting error  "failed to connect to exchange server".

Some points to consider

- I was able to receive emails on my cell when my mailbox was in exchange 2010.

- From Exchange 2013 I'm able to see the two Exchange 2010. I'm not able to see Exchange 2013 db from Exchange 2010.

- In exchange 2013 I configured receive and send connectors to 2010 and external URL

-All our inbound and outbound email traffic are going first thru McAfee email gateway and than forward to one of the exchange 2010. Auto discovery point to 2010 server.

- Exchange 2013 use the default certificates

Thanks in advance

• Edited by sAvak Saturday, February 28, 2015 2:01 AM

No. And I found out I'm only able to receive emails when I'm connected to the internal WI-Fi and put the actual cas server name. When I use mail.companyname.com I'm not able to connect.

• Edited by sAvak Monday, March 02, 2015 12:45 AM

Did you point the mail.company.com dns record to the 2013 CAS?  From your comments above about Autodiscover pointing to the 2010, i'm assuming not...

For coexistence, and clients to connect to a 2013 mailbox, DNS needs to point to 2013 for all services.  2010 does not know how to communicate to 2013, however 2013 does know how to communicate with 2010.

That's why I asked what I just asked.  That's what needs t

OK. Thanks. I'll try to do it later today.

I'm just wondering if 2010 cannot see 2013, how I'm able to receive emails from users that are in 2010.

• Edited by sAvak Monday, March 02, 2015 6:21 PM

It's not that 2010 cannot see 2013.  I probably should have been a little more spcecific :)

Exchange 2010 does not have the capability to proxy a 2013 user to their mailbox on a 2013 mailbox server. 

2013 was written with the capability to proxy 2010 users to 2010 CAS from a client access standpoint.

The 2010 HUB has the capability to send messages to 2013 users as it will determine that the user is on a different version of Exchange and then communicate with the HUB role of 2013 via SMTP, rather than directly delivering to the mailbox as it would if it was delivering to a 2010 mailbox.

I point mail.company.com to exchange 2013 and I was able to get emails on my mobile. But than all users on exchange 2010 stop getting their emails. It seems 2013 cannot proxy 2010.

After some digging, I found this article that fix the issue.

http://www.techtalklive.org/ttlblog/Pages/Exchange-2010-2013-Coexistence.aspx

Thank you for your time.