We're running in a hybrid situation. We use Google for email and calendar but we're beginning to use other Microsoft products in our tenant. We've been testing Bookings and have set up our test users on the Outlook side to forward all their emails to their Google accounts. So this includes any confirmation emails coming from Bookings. It works fine for a while but occasionally an email won't be accepted by Google and I get this message in my Outlook:
mx.google.com gave this error: [18.104.22.168] The IP address sending this message does not have a PTR record setup. As a policy, Gmail does not accept messages from IPs with missing PTR records. Please visit https://support.google.com/mail/answer/81126#authentication for more information. q8si5054529qtb.342 - gsmtp
If I do an nslookup on that address it's fine. This has happened on 8 different email addresses. I realize this is probably not a Microsoft problem and should really never happen, but I was wondering if anyone else has encountered this issue before.