multiple exchange accounts in iCal

I remeber a thread here a while ago asking something similar. While we did not have a verified answer, it seems you cannot have multiple accounts to the same server. (Possibly even to the same domain.) I do have iCal configured with multiple Exchange accounts, however each is on a completely separate server & domain. (i.e.: email on client's email servers, independant of each other.) But accounts on the same server, it seems that the Exchange server will reuse the credentials of your existing connection session. Windows & Outlook has a similar restriction when logged on to the domain that is also authenticating the Exchange server, although it appears to be more of a Outlook limitation. But to me that hints that Microsoft didn't spend much programming effort with multiple Exchange accounts. (And Macs haven't gotten much respect over at the MS Office development team. 😠 )

One workaround would be to use IMAP for one (or both) of the accounts. IMAP wouldn't work for calendar and such, but if you just need email, IMAP may be acceptable.

I've found the same problem in OS X Lion, with Mail, iCal and Address Book getting confused when two Exchange accounts on the same server are configured, resulting in either missing or duplicate entries (despite everything appearing fine when accessing the accounts individually via Outlook or OWA). iOS doesn't have any problem with this setup; two Exchange accounts on the same server work perfectly; the issue seems specific to Mac OS X.

After some experimentation I've found a workaround. Since the issue crops up with two Exchange accounts on the same server, it seems possible to trick OS X into thinking the accounts are on two separate servers through a little DNS manipulation (which I realize may not be a practical option for everyone). Here's what resolved the issue for me:

• My external and internal DNS FQDNs for the mail server were mail.mydomain.com.
• I set up a new DNS entry - mail2.mydomain.com - as a CNAME for mail.mydomain.com.
• On my Mac, I set up Exchange account #1 with the server set to mail.mydomain.com.
• I then set up Exchange account #2 with the server set to mail2.mydomain.com.

Even though both FQDNs resolve to the same IP, this seems sufficient for Mac OS X to consider them as separate servers, elliminating the problems I had before when I set both Exchange accounts to the same mail server FQDN.

I've only tried this on OS X 10.7 Lion, and the recent 10.7.1 update, although I wouldn't be surprised if the same trick works for earlier versions of OS X.

this seems to be a great workaround - if upgrading exchange to 2013SP1 will not remedy the issue I'll try this.

Actually only having the issue in Mail (iCal seems to work ok with multiple exchange accounts)

I've actually not had to worry about this for quite some time - Apple and/or Microsoft seem to have resolved the issue. I can now set up two Exchange accounts on the same server without an issue (no need for any DNS tricks). I'm running iOS 8, OS X Yosemite, and the latest Exchange 2013, but I didn't have the issue with iOS 7 or OS X Mavericks either - I don't recall exactly when it went away but you shouldn't have any problem now.

in my current setting I still have problems with mail - where one of the "multiple exchange accounts on the same server" will freeze.

But we are still on EXCHANGE 2010 SP1, so I hope the upgrade alone will fix it.