Email not readable since upgrading to Mountain Lion

Question

Since upgrading to Mountain Lion, I am not able to read my email in the upgraded version of Mail.  All my emails ON MY MAC are readable as normal, but my Inbox emails are there and I can read the single line information (From, Subject, Date Received, Mailbox) for all my emails but when I try and open one I get the revolving spindle wheel and Loading message.  My sent box appears empty unless I send a test email and then all my sent emails appear but again when I try and open one all I get is the same as for my inbox emails.  If I quit and reopen Mail, the inbox does not change but all my sent emails "disappear" again.  Is this an indexing problem or do I need to rebuild my mailboxes.  Although I have back ups, I do not want to take any action to make this situation worse.  Any help would be appreciated.

Answer 1

Hi,
When you start Messages fro the first time you are asked for an Apple ID
When this is verified and entered it appears in Messages Menu > Preference > Accounts and is Enabled.
The App should have also picked on on those iChat Accounst you had before.
These should be Enabled if they were when you last used iChat.
Exactly which "Accounts" are logged in can be seen in Message Menu > Accounts and will include the iMessage "Account" and Bonjour.
In the Window menu you will see CMD +0 for the Messages window and CMD+1 for the "Buddies" window which is a combined list at this stage.
Go to the Preferences > General Section and Untick the "Collect all accounts into one list".
This will give you separate iChat type Buddy lists.
You can check if that account/Buddy list is set to Invisible or if in the Preferences > Accounts > Security you have settings that will block some people from seeing you as On line.
You are saying Buddies can see you as On Line which implies they are still sending to your AIM based Names (@Mac.com is a valid AIM Screen Name)
I am not sure from your post if you are trying to iMessage their email IDs thinking they are Apple IDs and that they are using Messages as well.
There is no Buddy list for iMessages side
No-one can tell you are "On Line" until they have your details in the "To" spot in Messages with the correct iMessaged contact info (iPhone Number or Apple ID)
Obviously an Apple ID can be an email or look like one.
In some cases they are also valid AIM Screen Names as well.
In the case or the @mac.com name you may have linked this Apple ID to iMessages as well.
11:31 PM      Saturday; August 11, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
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"Limit the Logs to the Bits above Binary Images."  No, Seriously