Exchange Server 2016 and Office Online Server Process Flow

Here is the process flow of how Exchange Server handles attachments when integrated with Office Online server. Exchange uses discovery URL to ask Office Online Server which files types it can view and edit. Office Online Server returns table of supported file types. User opens mail with attachment that matches one of the file types Office…

Cannot enable UM for users

You cannot enable UM (Unified messaging) feature for users and get following errors. Enable-UMMailbox -Identity <> -UMMailboxPolicy <> -Extensions <> -PinExpired:$true -SipResourceIdentifier <> Exception: Mailbox <> couldn’t be initialized for Unified Messaging: There was an error accessing the mailbox using EWS. The requested operation failed with ResponseCode “ErrorInternalServerError”. Details : An internal server error occurred….

Mailflow issue from Exchange On-Prem to Office 365

You are on Exchange Hybrid environment and sending/receiving emails to/from Office 365 via specific Send Connector/Receive Connector which has TlsCertificateName attribute configured and EOP is doing certificate validation for Inbound/Outbound SMTP connections. You might see any of the following errors in the queue/Protocol Logs. –> 454 4.7.5 The certificate specified in TlsCertificateName of the SendConnector could not be…