Redmine

Sorry, I cannot get your intention.
Your patch send mail to assignee, right?
Your patch change behavior.
I think it is better to add checkbox on issue form such as ChiliProject.
https://www.chiliproject.org/issues/310

My intention is related to PRIVATE issues only. While private issues are hidden to the project members except the author and the assignee, the email notifications are distributed to all project members. And that's wrong, I think.

Karel Pičman wrote:

While private issues are hidden to the project members except the author and the assignee,

It is not true.
Private issue visibility can be defined at role "Issues visibility".

You're right. From that perspective my patch is wrong. However, the problem persists. In case of an update of a private issue, all members of the project get notifications despite the fact they are not allowed to view the issue.

Karel Pičman wrote:

all members of the project get notifications despite the fact they are not allowed to view the issue.

Really?

source:tags/3.1.1/app/models/issue.rb#L889

    # Remove users that can not view the issue
    notified.reject! {|user| !visible?(user)}