No Mail Flow On-Premises To/From Office 365
KB ID 0001631 Problem I upgraded my On-Premises Hybrid Exchange server recently, from Exchange 2016 to Exchange 2019. I remembered to add the new server onto the Office 365 send connector, but there was no mail flow between an on premises mailbox and an office365 mailbox? Solution This happens because, (even if you are using the same certificate on the new and old servers) the certificate that is used for TLS security between your...