Multi-purpose Internet Mail Extensions (MIME) is an annoying standard. The use of Internet Engineering Task Force MIME email between consenting adults is fine. It's a useful way to send a picture of the family to grandma. But unless the sender knows what software the receiver uses, MIME can be a way to standardise the transmission of gibberish. If you send me a perfectly standards-compliant MIME message containing an AutoCAD drawing, you have sent me standards-compliant gibberish because I don't have AutoCAD support on my machines.
MIME is also a way to standardise the transmission of maximally inefficient messages. It's not all that unusual for me to get a message of more than one million bytes whose useful content is less than 200 characters. The rest is Microsoft Word overhead and fancy stationery complete with multicolor logo and a list of corporate management. It sure is pretty, but it's no more informative than just sending the 200-character message by itself. Getting such a message does not put me in a cooperative mood, especially if it just took me 10 minutes to download it to my desktop in a hotel room. Transmission efficiency is higher if the message is in HTML (the web protocol), but unless you are using a web-based mail reader - which I do not - the message looks like a newspaper that was used to wrap up an order of fish and chips.
So for message size, software compatibility and message readability reasons, I've always asked people to send me plain text email. But now there is a growing number of privacy and security reasons to insist on it. MIME-transmitted Word files can be full of viruses, executables can destroy your disk and HTML messages can tell the sender when you open the message and even send a copy back to the sender of any comments you might add when forwarding the message to someone else. None of these problems occur if it's a plain text message.
It's particularly annoying that many email packages come preconfigured to be in abuse mode, and it can be hard to figure out how to tell them not to send pretty messages. Finally, to me it's a sign of ignorance or arrogance to send nontext messages to mailing lists. The sender is implicitly assuming that all list subscribers use the same software they do and that they all want to waste download time.
Disclaimer: Ignorance, arrogance and Harvard do not generally go together, so the above is my own opinion.
Bradner is a consultant with Harvard University's University Information Systems. He can be reached at email@example.com.