The Universal Thread, in order to avoid the auto reply, when someone goes on vacation, for mailing list users, will not accept someone to reply to himself/herself from the mailing list interface.
There is just no way we can accept that situation here. I guess any mailing list servers should not accept that either.
This was resulting in an infinite loop which would have created thousands of unnecessary duplicated messages per day.
This can also result in an auto remove from the mailing list.