If you are backing up or migrating from one server to another, you most likely will at some point be dealing with server A using the 'Sent' folder syntax with server B using the 'Sent Items' folder syntax and possibly even server C using the 'Sent Messages' folder syntax.
This page has been created during such an exercise, to provide a simple explanation, with examples, in order to help you get the job done !
The magic of using imapsync provides an option known as regextrans.
The regextrans option can be used, with a regular expression syntax, to map all emails being migrated/sync'ed/backed-up/etc from server A into a differently named folder on server B.
In this example, server A is an Office365 server, which uses 'Sent Items', and server B is a Zimbra server which uses 'Sent'.
Down to it
A completely fabricated example will look something like the following:
Linux # imapsync --host1 <source server> --user1 <source user> --passfile1 ~/.<a file with user1 password> --ssl1 --host2 <target server> --user2 <target user> --passfile2 ~/.<a file with user2 password> --ssl2