Setup mailbox folders named:
x-snooze-1
x-snooze-2
x-snooze-3
...
x-snooze-7
The number in the mailbox specifies for how many days mails should be snoozed.
By typing "m" and then "x", you can quickly move an email into the snooze folder.
Clone this repository and run:
imap-snooze.py --user fastmailusername --password application-password
Warning: only use on machines which you own. Other users on shared machines can often access the command line arguments and can consequently steal your password.
Warning: this is beta software. I use it myself, but this is an early prototype, which may have serious bugs.