I did some digging and found that the IETF recommends lines in message headers contain no more than 78 characters. This is to avoid some software from inadvertently truncating or poorly wrapping a long message header. Therefore, if one line contains "from: email@address.com", an email address should contain no more than 72 characters (78 - the 6 characters 'from: ').
In practice, I usually accept 128 characters, but I guess that's just always been a willy-nilly decision.
Anyway, does anyone have more insight?
p.s. I'm bringing this up because my 33 character email address didn't work at DivvyShot and I became ENRAGED.
