You can select all of the mail message and then forward them to yourself as a digest. You set a subject that matches and now all of this is in one message.  That said, most of us simply create a folder and put all of the mail on a specific subject/customer/identity into that folder and then attach a matching identity to that folder.

Is there a  way to combine messages from the same sender into one message?  other than cut and paste which can become tedious.

What do you want to do exactly?

Combine them when you download them?

Combine them afterwards for archiving purposes? 

[quote user="François Blais"]

What do you want to do exactly?

Combine them when you download them?     

Combine them afterwards for archiving purposes? 

[/quote]

I want to be able to combine messages received and/or sent to customers into a digest or archive. Thanks