I received an e-mail message this morning. The subject said: "Your user rights have changed on Wikipedia"
The contents said: "Your user rights were changed by <admin>. You are now a member of this group: <user rights group>."
Problem: There are a couple hundred Wikipedias. Which one was this?
Well, if you copy or click through the link, then you can discover the answer (in this instance, it was a test wiki), but the message itself ought to include the name of the wiki, including the language. The subject line ought to read, "Your user rights have changed on the Test Wikipedia", or "Your user rights have changed on the English Wikipedia", or whichever Wikipedia is relevant.