not really unless you are using POP and are really familiar with the file system. In which case copying folders is a bit like copying the filter rules.dat files. The major issue is account from profile to profile are not necessarily having the same location or references, so really only "internal" folders for the account can be "just copied"

Thanks Matt! The account with folder structure I was hoping to clone is IMAP on my server. Target accounts are Gmail (IMAP) and other accounts on the same server and with different domains.

If the account is IMAP, then the folders will download from the server, along with the mail they contain. So what is the issue with copying the filters?

No issue with copying the msgFilterRules.dat file, which can easily be copied from one T-Bird IMAP email account to any of the other 18 accounts on 3 other domains including local folders, and I'm done.

Everything works fine with the email filters I already have set up on one IMAP email account. I manually created about 500 different sub-filters (selection criteria) inside 45 different filter names with matching folders. So when email hits the Inbox on that particular account, it gets automatically Tagged, Flagged, Marked, Labeled, Color Coded, etc, and then moved to the appropriate folder. Or a different account. Or to Local Folders. It's out of my Inbox to deal with later. Or now. Just depends on the rules.

However, if I copy that filter to a different email account, it will fail to execute properly because the folder structures are either different or do not yet exist. It cannot move email to non-existant folders. That's why I want to clone them. Not the email inside, just the folders.

Does that help clarify what I am trying to accomplish?

Try copying the SDB folders (file system) from one account to another. It might work. Just be sure Thunderbird is not running when you do the copy.