We would really have liked to use afew for this, but it has severe
performance problems, for example:

https://github.com/afewmail/afew/issues/319

And that's just one of the issues... I couldn't actually figure out
how to do a bunch more stuff in afew, particularly the `move` plugin
just doesn't work for me because it operates on a single folder at a
time. Modifying this would involve forking the entire project, as the
`move` functionality is not a plugin that is easily modified.

This is a known bug, that said:

https://github.com/afewmail/afew/issues/314

But generally, I'm not sure that my "sync tags to mailbox" pattern
fits well with afew's notion that it only processes "new" messages,
which seemed to be geared more towards a "single workstation"
approach.