It would be convenient to be able to customise email notification subject. One example would be adding priority tag or even custom field.

The idea is to have better visibility for critical issues, those could be marked with priority or even emoji so it wouldn't be lost in all notifications, e.g. instead of

[Issue OD-1234] (Updated) New important issue

it could look like this

[Critical] [Issue OD-1234] (Updated) New important issue

Or even (I think doable if same Groovy simple template would be used as with email template available right now)

[🔥] [Issue OD-1234] (Updated) New important issue