Maintenance Mode

When you follow the steps to put EXCH01 into maintenance mode as outlined, you should not lose any emails. The commands you listed are designed to ensure that email flow is managed properly during the maintenance process. Here’s a brief overview of what each step does:

1. Set-ServerComponentState: This command puts the Hub Transport component into a draining state, which allows existing messages to be processed while preventing new messages from being routed to EXCH01.
2. Restart-Service: Restarting the transport services helps to ensure that any pending messages are processed correctly.
3. Redirect-Message: This command redirects messages pending delivery to EXCH02, ensuring that emails continue to flow even while EXCH01 is in maintenance mode.
4. Suspend-ClusterNode: This prevents EXCH01 from becoming the Primary Active Manager (PAM) during maintenance.
5. Set-MailboxServer: These commands disable database activation and block auto-activation, ensuring no databases are active on EXCH01.
6. Set-ServerComponentState: Finally, this command puts the server into maintenance mode.

By following these steps, you effectively manage the email flow and minimize the risk of losing emails during the maintenance of EXCH01. However, it is always a good practice to monitor the email flow and ensure that all processes are functioning as expected before and after the maintenance.

References:

• Managing database availability groups
• Manage database availability groups in Exchange Server

Hi Rising Flight,

Thank you for posting your question in the Microsoft Q&A forum. 

Regarding your ask about whether the maintenance script will avoid losing emails, I reviewed the references and the QA Assist notes and would summarize the key insights as follows:

• Your script closely aligns with Microsoft guidance that the QA Assist cited, and also mirrors common community runbooks. However, it appears to match most closely an older Microsoft article aimed at Exchange Server 2013. While the steps and cmdlets are still technically valid, that article is dated.
• To be fully confident and current, you should follow Microsoft’s newer, consolidated guidance for maintaining a DAG member: https://dori-uw-1.kuma-moon.com/en-us/exchange/high-availability/manage-ha/manage-dags#performing-maintenance-on-dag-members This page is the official recommendation covering modern versions (Exchange 2016/2019 and Exchange Subscription Edition) and reflects today’s best practices. Microsoft provides detailed notes and step‑by‑step instructions in that article, and because it’s the official recommendation, the procedure is designed to safeguard database integrity and prioritize data protection during maintenance (including moving active databases off the server and preventing them from moving back while you complete the work).

I hope the insight above is helpful.

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