/$LISTNAME/$MESSAGE_ID/t.mbox.gz -> gzipped mbox of thread
### Stable endpoints
-/$LISTNAME/$MESSAGE_ID/ -> HTML content (short quotes)
+/$LISTNAME/$MESSAGE_ID/ -> HTML content
/$LISTNAME/$MESSAGE_ID -> 301 to /$LISTNAME/$MESSAGE_ID
/$LISTNAME/$MESSAGE_ID/raw -> raw mbox
-/$LISTNAME/$MESSAGE_ID/f/ -> HTML content (full quotes)
/$LISTNAME/$MESSAGE_ID/R/ -> HTML reply instructions
### Legacy endpoints (may be ambiguous given Message-IDs with similar suffixes)
+/$LISTNAME/$MESSAGE_ID/f/ -> HTML content
/$LISTNAME/m/$MESSAGE_ID/ -> 301 to /$LISTNAME/$MESSAGE_ID/
/$LISTNAME/m/$MESSAGE_ID.html -> 301 to /$LISTNAME/$MESSAGE_ID/
/$LISTNAME/m/$MESSAGE_ID.txt -> 301 to /$LISTNAME/$MESSAGE_ID/raw