Things that need escaping seem to be getting removed entirely in talk page notification emails.
For instance, the email for https://www.mediawiki.org/w/index.php?title=User_talk:Emufarmers&diff=1037143&oldid=1037136 consisted of:
Jack Phoenix left a message on your talk page in "|".
So I heard that orange is your favorite color, especially when wrapped in a nice little that has class="usermessage"... --
Version: unspecified
Severity: normal