The core problem:
Steps to reproduce:
-Create page with user mentions.
-Get page archived.
Result: every user mentioned in the original page receives an email notification when the new page is created in the archive space: "... mentioned you on a page".
This is unfortunate. The mention feature should be turned off when pages are archived.
It is not totally trivial to resolve it, as it is not possible to turn off mentions for the time of creating a single comment.
Confluence User Manual also suggests turning off the "Confluence Mentions Plugin" to bypass this feature: https://confluence.atlassian.com/display/DOC/Using+Mentions
It feels a little unsafe for one plugin to disable and re-enable another one, but we will consider implementing it.
(Workaround: if you execute archiving manually, then you could turn on/off the other plugin for yourself.)