If you are literally trying to move an active folder under one email account to another, rather than to another location in the account hierarchy in which it already resides, you cannot do that directly.  Accounts are their own little worlds, and the folders are associated with those accounts which, if they're accessed via IMAP, are stored on the email server for the account.  Even if it's two accounts from the same provider, these exist in isolation from each other.

There are ways to move messages across accounts, but they involve things like archiving the messages on the source account, then importing from the archive in the destination account, or forwarding all messages in a given folder from the source account to the destination account if there are few enough to make this practical (or doing it via scripting).
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Brian - Virginia, USA - Windows 11 Pro, 64-Bit, Version 22H2, Build 22621; Office 2016, Version 16.0.15726.20188, 32-bit; Android 12 (MIUI 13)  

I recoil from any definition of the relationship between artist and audience that is predicated on the audience claiming a sense of betrayal over who someone is or isn’t outside of the context in which they’re performing. What we know about an artist’s personal identity can be interesting and even illuminating; what we are entitled to know is … nothing, basically.

            ~ Mark Harris, Is Celebrity ‘Queer Baiting’ Really Such a Crime?, 

               T: The New York Times Style Magazine, Feb. 6, 2023

Sounds like a lot of work. What I found is the first folder moved included all its emails. Then the next 5 folders moved and the emails didn’t. I didn’t check before moving the folder if there were emails in the folder. Then the next few folders were moved including the emails in that folder. I wonder if there is a setting that can be set to delete emails in a folder after a certain time. The folders that were moved along with the emails within the folder have emails that go back a few years.

If you are literally trying to move an active folder under one email account to another, rather than to another location in the account hierarchy in which it already resides, you cannot do that directly.  Accounts are their own little worlds, and the folders are associated with those accounts which, if they're accessed via IMAP, are stored on the email server for the account.  Even if it's two accounts from the same provider, these exist in isolation from each other.

There are ways to move messages across accounts, but they involve things like archiving the messages on the source account, then importing from the archive in the destination account, or forwarding all messages in a given folder from the source account to the destination account if there are few enough to make this practical (or doing it via scripting).
--

Brian - Virginia, USA - Windows 11 Pro, 64-Bit, Version 22H2, Build 22621; Office 2016, Version 16.0.15726.20188, 32-bit; Android 12 (MIUI 13)  

I recoil from any definition of the relationship between artist and audience that is predicated on the audience claiming a sense of betrayal over who someone is or isn’t outside of the context in which they’re performing. What we know about an artist’s personal identity can be interesting and even illuminating; what we are entitled to know is … nothing, basically.

            ~ Mark Harris, Is Celebrity ‘Queer Baiting’ Really Such a Crime?, 

               T: The New York Times Style Magazine, Feb. 6, 2023