I agree with most everything Eric says. Particularly as one who receives the list in digest form, I have no use whatsoever for HMTL mail, which always loses its formatting when digested(!). BUT... The header on his message is over 2,500 characters long! This is typical of list messages. It is also typical of list servers (although I do not know about this particular one) that the header is counted towards the limit. I have personally bumped into this limit with my own emails in the past. Your practical limit is therefore a whole lot less than 5,000 characters.