$ python cli.py --help

Usage: cli.py [OPTIONS] COMMAND [ARGS]...

Options:
  -h, --host TEXT       IMAP server  [required]
  -u, --user TEXT       username  [required]
  -p, --password TEXT   password  [required]
  --debug / --no-debug
  --help                Show this message and exit.

Commands:
  move   moves emails from one folder to another

If you need to move emails from one folder to another in a mailbox, one way is to use a mail client, download all the emails, then drag them to the other folder. I suspect most mail clients will use something like COPY ... EXPUNGE, but even if they don't, downloading all those message headers is a little inefficient (especially as the client will have to resynchronise.

Instead, you can use this move script, which uses the IMAP4 MOVE command. I used this to move around 30k messages from one folder to another when I migrated from Google Mail to Runbox so it works pretty well, and inserts a 100µs rest every 250 messages anyway.

Unfortunately I haven't found a reliable way to operate over a range of UIDs, so this executes the MOVE on a per-message basis, which makes it a little slow. It reports progress every 250 messages.

For example, when moving emails from Gmail's "All Mail" folder, to my newly created "Archives" folder:

$ python cli.py -h imap.server.com -u me move -f "[Gmail].All Mail" -t "Archives"

Leaving out the -p password option causes the programme to prompt you for a password (which is better than leaving it in plaintext).