Should e-mail be sent as plain text or HTML?
Most modern e-mail programs allow you to send messages in either plain text or HTML (also known as styled text).
With plain text, there's only one font, no colors, no bold, no italics, no pictures. Just plain ol' text. On the other hand, HTML-formatted messages can contain multiple fonts, bold, italics, colour, pictures and other formatting.
So why do I stick with plain text when I send e-mail? Well, I'm glad you asked. :-)
It comes down to this: there are many reasons not to open e-mail messages that contain HTML; thus, if you send HTML-formatted e-mail it's LESS LIKELY TO BE READ.
Let me explain why I (and many others) filter out most of the HTML-formatted e-mail that I receive:
1. HTML-formatted e-mail can contain destructive software.
Destructive software can be embedded within the HTML of the message. For instance, the "Forgotten" worm was written in Visual Basic Script and spread WITHOUT any attachment.
Instead, the worm code was embedded into the HTML formatted message body.
Similarly, the "I Love You" worm exploited an ActiveX vulnerability and was executed just by VIEWING or previewing the e-mail message.
In neither of these cases did you have to open an attachment to be infected. Just viewing the message was enough.
2. HTML-formatted e-mail often contains porn.
Porn sites love html e-mail because it allows them to send pictures that they hope will lead to more visitors to their sites.
3. Viewing HTML-formatted e-mail can lead to more spam.
(The following explanation is a little technical. Feel free to skip to the next point if it's not your cup of tea.)
Let's say that a spammer sends you an HTML-formatted e-mail containing a small picture (even a single pixel) that's stored on their server. When you open the message, that picture is fetched from their server.
Normally, this would only give them your IP address (which they could find by looking in their server's logs), but that's not enough to identify you. A smart spammer, though, will make the URL to the picture something like this:
The "fbiouwgkxmsyts" part is your e-mail address, but it's encrypted so that you don't recognise what they're doing.
So, just by VIEWING the message, you've confirmed to the spammer that your e-mail address is valid and currently in use. This makes it much more likely that you'll receive further spam from them and anyone that they sell their mailing list to.
4. HTML-formatted e-mail is larger and thus slower to download.
For all these reasons, many people dislike receiving HTML- formatted e-mail and thus automatically filter much of it out without reading it.
Of course, if it comes from a friend or colleague that's another matter. My filter's "white list" always lets their mail through.
But if you're sending e-mail to people outside your business or circle of friends then it's more likely to be read if you stick to plain text.