If you want the auto-reply like out of office mails to be updated in the existing incident comments, you need to make sure and perform below things:
- Sender mailbox is sending the Out of the Office mails to Servicenow instance. This can be verified from their sent items.
- If sender has sent the mailbox, make sure it has been received by servicenow instance from sys_email table or email log.
- You will have to use "Identify email as reply by these prefixes" to add "Auto-Reply" type prefixes or any prefixes which can be identify the automatic reply.
- Remove auto-reply from the ignore header entry
- Many times user does not allow or forgot to allow Automatic Replies from outlook for "Outside my organization". See below screenshot: