Attachment reminder functionality should use language used in e-mail instead of the system language
As requested in #648 (comment 698761).
Feature Summary
Geary already has a reminder functionality which checks for words like "attachment" or "enclosed". These words are also already translated in the most languages.
Unfortunately, the checking for the words "attachment" or "enclosed" (or a variant) uses the system language instead of the language used in the e-mail.
But in my setup (and I am sure that is also the case for many other people), I have my system in English but still write a lots of e-mails in my native language (in my case German). While the attachment reminder functionality then works fine for e-mails I write in English (e.g. for the word "attachment"), it does not for e-mails written in German (e.g. for the word "Anhang").
How would you like it to work
Instead of taking the system language for checking for the words, Geary should use the language used in the e-mail.
If this can not to be determined (reliably), Geary could use the languages configured for spell checking.