A colleague just wrote me "I notice you always use plain text. Is this for asthetic reasons, or is there a technical reason?"
It's a good question, and one of my pet peeves; especially in a corporate environment.
Actually there is a very good technical reason. If your recipient uses any mail client other than Outlook (or notes if you're composing in Notes, which is actually worse), non-plain text formatting will not look right; and may in fact completely screw up your email.
Lots of people use text coloration or special fonts in email to denote divisions, or add notes etc... But if anyone reads those things on anything other than the program you wrote the email with, they aren't going to know what's going on.
Yes many clients support RTF or HTML email, but they all render it slightl differently; especially on Mac and UNIX systems.
The worst part is when peope cut and paste tables from word docs into emails. If you read them in anything other than outlook it completely hoses the message, and can make it entirely unreadable.
Also, many spam, virus, and active content filters will actually BLOCK emails which contain lots of formatting, html, embedded objects etc... Stationary is one of the biggest offenders here; it gets blocked by a ton of spam filters. The reason for this, is because active content can be embedded in heavily formatted emails which can infect systems with viruses etc... and because hevily formatted emails happen to look a lot like spam, which is often web pages sent as email.
Email is not a multi-media communications format. Email is actually an RFC standard, so it can be read by any program, on any computer, in any country. Email should not use special fonts, or have embedded html, scripts, graphics etc... It is supposed to be plain text, with attachments. If it isn't you're breaking other peoples systems because you want some whizbang, and that's just kinda clueless and rude.
Unfortunately, Microsoft has never cared much about breaking everyone elses systems; and if MS allows people to do it, they will do it. Since the vast majority of people think all email is whatever MS tells them it is, they go about with stationary and funky fonts, not knowing any better.
I have a personal policy. I read all email in plain text, and if the email is unreadable in plain text, I delete it. Oh and don't send me anything important or confidential unencrypted please; but that's another rant for a later time.