Warn user about enabled autoresponder

[ChristophWurst]

Is your feature request related to a problem? Please describe.

As a user, I enable an autoresponder before I go on vacation or when I'm sick. At my return, I might not think about disabling the responder again and so the mail server would still respond to my incoming emails.

Describe the solution you'd like

Show a visual warning that an autoresponder is turned on.

This could look similar to

Describe alternatives you've considered

N/a

Additional context

N/a