It is difficult to get business owners of sites to communicate with their user base. They have mixed success in getting the message about site changes in front of their users. The ability to create a temporary page to communicate changes would be useful in addressing this. As admin we are asked by site owners how they can let every site user about the changes and in the event of a large multi-site migration this is too much of an overhead to try and retrieve lists of email addresses for SP2010 and SPO using PowerShell.

A traffic light system might work to show a site is in migration planning, then being migrated, then migrated and the new URL.

I’m open to suggestions but the thing we are trying to solve is to enable site owners (or admin) to effectively message all of their users (internal and external).
Thanks