Remember when yEnc showed up, and discovered that most NNTP servers could actually deal with mostly 8-bit bodies, and it made transferring files that much more efficient?
It's still used in binary groups to this day. It's too bad that it never really was used in email and most email clients didn't support it.
IIRC, NNTP, SMTP, and I believe IMAP servers do not treat any character as significant from a protocol standpoint other than ascii NULL (0x00), CR (0x0D), LF (0x0A), and . (0X2E) (the last only when at the beginning of a line). Those are the only 4 characters that yEnc escapes for encoding purposes.
Good times, indeed!