Mac OS X 10.6.2 Update Changes Mail Line-Wrapping

According to the release notes, the Mac OS X 10.6.2 update “improved line wrapping compatibility when sending to certain mail clients and Microsoft Exchange Server”. It looks to me like Mail now uses the "quoted-printable" encoding by default and has dropped support for sending the "format=flowed" content-type. AFAIK, Mail has never had a user-configurable option to toggle between the two modes.

I think Apple have done this because Outlook doesn't understand how to re-wrap format=flowed, but does handle long lines with “quoted-printable” correctly.

Why does this matter? Most mailing list software handles quoted-printable-encoded long lines correctly. But the correct behaviour is not the desired behaviour. It also matters because the use of "quoted-printable" to send lines of over 998 characters in length is in violation of some of the RFCs and may cause legacy software to choke.

For more details, see:

Last updated: May 1st, 2010