$7.90

This plugin will allow users to set up an automatic reply to personal conversation when they’re not available. A new option will be added on Account Settings to users from selected groups. They will be able to enable the auto reply and type the auto reply content. Users with this feature enabled will view a global message warning about the auto reply and will show a link to disable it.
Invision Community Auto Reply to PMs 2.2.1

$7.90