Forum Discussion
Exchange Hybrid - On-Prem mailboxes can't send to Online mailboxes
We're now running Exchange Hybrid OnPrem: Exchange 2019 latest patch. On-Prem mailboxes are not able to communicate with mailboxes in Exchange Online in any way. The other way around is working ...
Lussy150It sounds like an issue with either the send connector to Office 365 in your on-prem Exchange organisation or the "your org to Office 365" connector in EXO. Confirm that your Exchange server can make an SMTP connection to Exchange online. I'd guess the connection is being blocked...either by your network or because the certificate is incorrect and EXO is rejecting the connection (you can use certificates or IP addresses to identify the on-premises Exchange server making the connection)