We running exchange 2013 on prem and in hybrid mode with office 365. We use barracuda essentials for spam and archiving. We have been seeing a lot of rejected messages in the logs of the Essentials stating the exchange server is rejecting the emails even though the users are valid. it is happening coming from multiple domains.
Rejected (smtp.abc.org:25:550 5.1.1 User unknown)
Allowed Sender Policies (header:Lisa.xyz@domain.com)Rejected (smtp.abc.org:25:550 5.1.1 User unknown)
both were going to valid working email accounts on our domain that have mailboxes still on premise.
I have checked and updated our spf records and all other records look fine. The users get emails from other outside companies
Thank You in advance
| Allowed | Sender Policies (header:Lisa.xyz@domain.com) | Rejected (smtp.abc.org:25:550 5.1.1 User unknown) |
| Allowed | Sender Policies (header:Lisa.xyz@domain.com) | Rejected (smtp.abc.org:25:550 5.1.1 User unknown) |
| Allowed | Sender Policies (header:Lisa.xyz@domain.com) | Rejected (smtp.abc.org:25:550 5.1.1 User unknown) |
Stonecold31666