The "Microsoft DMARC validation for receiving email" section near the end, and the link that it contains, reminds me of a problem that I wish Microsoft would address, and that is what we're meant to do to realistically work around the effects of the mandatory DMARC policy change made to Outlook.com. As the comments in that thread point out, and as other threads such as the one at https://answers.microsoft.com/en-us/outlook_com/forum/outlk_com-outtop_email/outlook-redirect-rule-stopped-working-access/32a19354-a0c7-4747-a1b5-5f4babd4b9cc?messageId=9c2b1b3d-e4c9-4cdb-aac4-2be1aec99397&page=1 go into in great depth about, that "Access denied" problem is subtle and vexing.