(Mailgun) Inbound route catch_all() not forwarding autoreplies

Question

This one has me stumped... I currently have one MailGun route setup... its a catch_all() that forwards all mail on my domain to my GMail account. For some reason, if I email somebody who has an autoreply (i.e. an out-of-office responder), I do not receive the autoreply message. I checked the MailGun control panel logs, and the autoreply never even shows up... its as if messages sent via MailGun don't trigger other mail services to send an autoreply? I've confirmed that my sent messages are received in the Inbox of the person with the autoreply active. I've also confirmed the behavior when sending to outlook and GMail users.

Help please! Thanks.

Answer 1

Here's a response I got from mailgun support:

We by default drop all system messages, NDRs, OOOs and auto-replies (they'll all have a null <> Sender header which don't allow).