ignore_by_title feature is to filter off unwanted (SPAM? auto-mailers? auto-replies?) emails before they create topics that must then be removed by hand.
It takes regex expressions and will block the email if matched:
lib/email/receiver.rb: def is_blacklisted? : Regexp.new(SiteSetting.ignore_by_title) =~ @mail.subject end
I believe Ruby does a case-sensitive match. It would be much more useful to do a case-insensitive search here just to catch people sending in unwanted emails with different casing.
Otherwise, say, in order to block the word
happy, I’d have to do at least the following: