Because of discussions today around issue #41675 and from
what I read in this wiki page, I somehow thought that only the .mbox
archive would be kept around and that the web archive would become
offline upon deletion.

But what happens is rather more to-the-letter what is said in this page:
the archive is kept around, html files visible on the web included.

I'm just clearing out the possible questions that I'll have (and
possibly others?) when I won't remember this detail by adding a quick
note about the web archive remaining online.

service/lists.md

@@ -51,8 +51,9 @@ To remove a list, use the `rmlist` command on `eugeni`:
 ssh eugeni.torproject.org sudo -u list rmlist LISTNAME
 ```
 
-By default, archives are kept. If that's not wanted, use the `-a`
-flag.
+By default, archives are kept (including the ones visible on the web via
+`https://lists.torproject.org/pipermail/$listname`). If that's not wanted, use
+the `-a` flag.
 
 Don't forget to update the [list of mailing lists](#list-of-mailing-lists) upon changes.