qtmmSendMail and text/plain vs. text/html

All,

 Our shop uses qtmmSendMail to distribute MIME documents as "Content-Type:
text/plain" - anything non-text is included as base64 encoded attachments.
This has worked for all our business partners as long as I've followed
RFC2822 and kept individual line lengths under 78 characters.

 Our latest project involves sending URLs in the message body, the length of
which can exceed 78 characters. Since the body of the email is sent as
text/plain, some email readers wrap the line at the 78th position, killing
the URL and causing confusion and unrest among some non-technical
recipients.

 It appears as though changing the content type to "text/html" will solve
the line-breaking problem but at the risk of breaking compatibility with
older mail readers or automated import processes. Some email clients address
this issue by duplicating the email body, once as text/plain and again as
text/html, including "Content-Type: multipart/alternative;" and letting the
email client choose which format to use.

 Does anyone have war-stories about this? To bring it back to the iSeries,
I'll mention that we've used a modified version of David Lelands' SndEmailR
program for years. Thanks, David. The mods to do the above aren't terribly
difficult but thought I'd ask if anyone else has dealt with this before I
start surgery.

Thanks, JK