"Reply by email" feature should be allowed to be deactivated for each GitLab user individually
When a user is informed about a specific change on GitLab, for example a newly opened issue, and if notification settings are configured in a way that the user receives a notification email, he can currently directly reply to that notification email and the reply is shown in the entity where the reply belongs to. (see documentation).
Request: Every user should be able to deactivate that "Reply by email" feature in his/her notification settings (in "User Settings" -> "Notifications").
Why should the deactivation of "Reply by email" be possible?
1. Emails are insecure because they can be read by everyone who has access to them. This means it is possible that anyone who retrieves the email from GitLab could spam the conversation in GitLab just by sending emails to the response email address. It is not necessary that the "man in the middle" has to authenticate against GitLab when sending that response email.
2. This is more specific to my special use case: I have a project where I also administer an external mailing list on nongnu.org. There are several people who are interested in newly created or closed issues, but they don't have a GitLab account for several reasons. To keep those users informed, I created a new GitLab user with the email address of that mailing list. Every time an issue for my project is created ore closed, an email is sent to that mailing list. Unfortunately, every user who is subscribed to that list can respond to this notification email and the response is shown in the GitLab entity. I therefore would like to turn that feature of for that "email distribution user account" in GitLab.
What do you think about it?