If I give sa-learn
Maildir mails to train it as spam, it takes them without problems, but when trying to use a mbox file containing spam emails from my personal Gmail account (using https://takeout.google.com/settings/takeout/custom/gmail), it doesn't like it:
$ grep -c '^From ' spam.mbox
390
$ sa-learn --progress --no-sync --spam --mbox spam.mbox
Learned tokens from 0 message(s) (0 message(s) examined)
So, it's clear that spam.mbox
contains emails (390 in fact), but for some reason sa-learn
decides to ignore them.
What could been going on here?