Is it possible to add further rows into the Subject line in an email?
From what I understand, the standard for email defines the ability for a subject header to be a maximum length of 998 characters, or, split over multiple lines (78 characters for each line max) using a technique called “folding”. However, MS Outlook 2010 doesn’t seem to allow for this feature and imposes a 255 character (1 line) limit for the subject header. From what I can tell, there doesn’t seem to be any settings regarding this in options and copy/pasting content with CRLF seems to only paste the top most line. My guess is that this one done to maximise compatibility with other email readers.
I've found a reference to the proper RFC from this stackoverflow.com thread: http://stackoverflow.com/questions/1592291/what-is-the-email-subject-length-limit.
The direct link is here: http://www.faqs.org/rfcs/rfc2822.html (Section 2.1.1).
An alternative solution to your problem might be to use custom forms in Outlook, which you can use to some extra fields to email messages, but I think for this to work your mail server would need to be MS Exchange Server.