I currently have a customer who connects to two exchange accounts on the same profile, one of which is on a local exchange, and the other connects using RCP/HTTPS to an external exchange on a different domain. The external domain has recently changed it's domain name so the address has changed  where outlook needs to point.

I can set the settings manually or recreate the account and it all connects correctly; however every time she logs out and back in the settings all change and point back to the old domain name on the external exchange.

This appears to be a common problem with outlook and most posts say to apply group policy to force the https address however I have one email on email@onedomain.com on the internal exchange and email@seconddomain.com on an external exchange. If I apply a GPO it will surely point both accounts to the same domain, and therefore still point one incorrectly.

Does anyone know how I can fix the settings from changing in the first instance, or alternatively apply a gpo to one specific account rather than both in outlook 2010?

After some further investigation, we only had a few accounts on the external exchange so we've moved their secondary domain to their onsite exchange.

Whilst it doesn't solve why the original issue happens, it has resolved the imminent issue.

check if this article helps:

http://blogs.technet.com/b/kristinw/archive/2013/04/19/controlling-outlook-autodiscover-behavior.aspx