I recently began getting complaints from people I emailed (mostly work-related) that the messages I was sending came out wrapped at a certain width, which was annoying to them especially as I often mail long messages.
I figured out that what these people had in common is that they were using Outlook or Outlook Express. I did some research and realised that Mail.app uses a recent SMTP extension, the format=flowed parameter to the plain/text Content-type. Without getting into details that would scare those of you with little knowledge of SMTP and MIME, this is essentially a way of sending plain text that is wrapped at a fixed width for transport, but can be reassembled as long lines on the receiving end. Apparently, neither Outlook nor Outlook Express (and, unsurprisingly, a rather old version of Lotus Notes my biggest customer uses) supported this extension.
Now what weirded me out completely is that I use Rich Text (i.e. text/html) to send e-mails. Without wanting to get into a religious flamewar, even though I've been e-mailing long enough to know what UUCP is, I'm a convert to Rich Text e-mail. Although I stay clear of patterned backgrounds and pink 72-point type for aesthetic reasons, I do appreciate the ability to make something italic or underlined, or insert a table or a bulleted list here and there. And yet my messages were being sent as Plain Text.
No more than a couple of clicks through Mail's help system and I had found the cause: if there is no special formatting in your message (no italics, bold type, different fonts or sizes etc.), as there often isn't in my messages, then Mail sends the message as Plain Text -- even if you've selected Rich Text. This has the unfortunate side effect of making your mail wrap at a fixed column (72, as a matter of fact) for those of your recipients unfortunate enough to be using some version of Outlook, either through ignorance or employer requirement.
So, what, I see you ask, dear reader, did you do to rectify this? Did you abandon Mail for another application (shock! horror!)? Make sure every message had some formatting (as if I would ever remember to do that)?. Au contraire, dear reader, there is a simple and elegant solution: If you don't already have a signature, create one, and make sure it has some formatting in it. If, like me, you think signatures are a waste of bits, you can do what I did: create a signature consisting solely of a period "." and make that bold, or italic. Now your outgoing messages will always be Rich Text, and wrap beautifully on Outlook readers, with the sole blemish being a tiny dot at the end.
And yes, dear reader, I did try using a space, and even some weirder invisible Unicode characters like the non-breaking space, which naive HTML coders are so fond of, or the less well known but equally useful em quad, but unfortunately, Mail won't let you have a signature consisting solely of non-printing characters. So I'm stuck with the dot. But still, at least I'm not stuck with my customers' complaints.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20051111065152472