Question : SMTP 500 error "Line too long"

My mail server is rejecting email from a particular person, other people on their mail server/domain can send me emails no problem.  This person is reported to be offsite however.  I can tell from my smtp logs that the failure occurs after the DATA command, here is a tidbit from my log:

1b45: Out: 354 Start mail input; end with .
2009-08-04 13:44:50 : SmtpReceiver: 1b45: DATA
2009-08-04 13:44:50 : SmtpReceiver: 1b45: oldstate = 3, newState = 4: wait rcpt
2009-08-04 13:44:50 : SmtpReceiver: 1b45: readStreamLine: Maximum line length overflow. possible loss of data
2009-08-04 13:44:50 : SmtpReceiver: 1b45: Message received from remote system: 3252 bytes, 0.062 secs, 52452 bytes per sec
2009-08-04 13:44:50 : SmtpReceiver: 1b45: Out: 500 Line too long
2009-08-04 13:44:50 : SmtpReceiver: 1b45: Message finished, error receiving: Excessive line length.

So basically there is an issue with this one person's local computer I think, their admin was able to send me test emails using the account in question.  The sending mail server is Exchange 2003.

Is the command issued too long, or is the data being sent too long?

Answer : SMTP 500 error "Line too long"

According to the SMTP RFC: (design spec)
http://james.apache.org/server/rfclist/smtp/rfc0821.txt

The line lenght is limited to 1000 characters per line (excluding leading extra . or CRLF, check the sizes section of the document)

So typing extremely long paragraphs without any CRLF into them might lead to this.
of listings of some automated software.
Sending files should be encasulated by MIME and mime has provisions to limit the linelength to much smaller amounts.