Procedure for Maintenance Announcements

Before doing any important system upgrade which may result in downtime, announce the update to your users.

In your message, clearly state the time the upgrade is expected to begin in UTC, what you plan to upgrade, and roughly when service will be restored. For example:

Jun 28, 2023: A scheduled upgrade will take place in 30 minutes at Jun 28 22:00 UTC. We are upgrading example.com users to OpenBSD 7.3. Service should be restored at around 22:30 UTC. Thanks for your patience!

Email

For major updates, send an email to users on the mailing list. For major updates, please cc team@ircnow.org and your team email support@example.com

IRC

Announce on #ircnow and on your #announcements and #team channel. You will also want to announce on any networks your team supports.
If ZNC will be affected, announce on ZNC using

/msg *status broadcast <msg>

You will need to repeat this every 5-10 minutes because some users may not see NOTICE messages.

Shell

Update /etc/motd to notify users of major changes
Write on users wall ?:

$ doas wall

Wiki:

Log major changes on your team's website