Escape password with extra special characters for Mailer

According to the documentation, I can surround a password with backticks, to allow for special characters.

The database section in the documentation also mentions, that one can use triple quotes, to achieve the same.

In my case, I cannot use the backticks as it did not work and cannot work, as suggested.

I tried using triple quotes, hoping that this would not only work for the database password. Unfortunately, this attempt was unsuccessful, either.

Now, I’m not sure how to escape the password properly. I am getting an authentication failure, when trying to send a test mail in the adminstration area of the Web UI.

The password itself is a 100% correct, works within other apps, perfectly fine.

How can I make the password work?
Is triple quoting for the mailer password officially supported?