Background: Exchange 2010/2013 and Microsoft 365 Hybrid environment.
We use scan-to-email on Xerox network printers, the SMTP is pointed to our on-prem exchange server 2010, port 25 and no authentication is needed. We also have an email relay connector set up for all printers on Exchange 2010. Everything has been working fine for many years.
After we added Exchange 2013 to the mix, the problem started and the Microsoft 365 mailboxes no longer receive the emails from the printer, however, on-prem mailboxes receive it just fine. No matter we use Exchange 2010 or 2013 as the SMTP server in the printer configuration, when I ran the email test on the printers, the emails were sent successfully but only on-prem mailbox received it and O365 mailbox never received it. NO error. I could not locate any trace or queue on either Exchange servers or Exchange online.
All regular email flows are working as expected. Any suggestion is appreciated!
Thanks
Calvin