Exchange email clients won't connect after upgrade from 2007 to 2010

I have everything working now...  I never did receive a migration confirmation email with further instructions!  As part of the migration, they should have told me BEFORE migrating that I would have to update my DNS zone file.  I used to be on the po2 servers, but now my mailboxes are on the w14b servers.  Once I logged into GoDaddy and updated my DNS entries with the new hosts, everything started working within an hour or so.

When Comcast upgraded my mailboxes, they moved them from an Exchange 2007 server to an Exchange 2010 server.  The DNS records for my domain were still pointing to the old server.  On the Comcast Business website, go to My Account -> Manager Tools -> Manage Email -> View DNS Settings.  You will see a section on the webpage that says "Configuring your mail server" and has a bunch of "Mail access type" names and the corresponding DNS names.  Make note of all of them.  Then, go to whichever Internet registrar maintains your DNS file for your domain. For me, that meant logging into GoDaddy.com and using their Domain Manager tool.  Edit your DNS Zone File by changing all of the CNAME entries that have comcast.net in them, and make them match the ones that you noted from the DNS list on the Comcast website.  For example, I had to change all of mine from "mail.po2.comcast.net" to "mail.w14b.comcast.net" and "smtp.po2.comcast.net" to "smtp.w14b.comcast.net", etc...  Change the CNAMEs and the MX records.  Once they are changed, save your DNS Zone File.  It will take an hour or so for the DNS changes to propagate across the Internet.  For me, after about an hour, Outlook on my laptop automatically popped up a message that said my settings had changed and it needed to restart.  On my iPhone, it just popped up a security certificate message which I needed to accept.  Then everything started working fine.

OMGOSH!! Thank you so much for this - I have been trying for hours to get my email to work - trying every combination I could think of in my Mail profiles - installing and uninstalling Outlook! UGH...I have an entire organization that I have to manage - we dont have an "IT" person - So to call anyone its 150.00 an hour - I also received an email that our Email was being upgraded - but it was to a service email we never check - so much to my surprise - we had no email and when I came in this morning my boss was not very happy. Called Comcast but they no NOTHING....its really frustrating - So thank you thank you thank you - changed everything - crossing my fingers it will update soon!!!!