For Outlook 2007, Microsoft removed the embedded Internet Explorer engine for displaying HTML e-mail and dropped in some half-baked solution. From Word. Apparently, the same engineer (an idiot) who thought that margins and padding in 'div's were bad (because Outlook is now pretty much incapable of that) also decided that support for blinking text is good.
The ancient, decrepit 'blink' tag isn't implemented, so how does one accomplish this atrocity? With 'text-decoration: blink'.
That's right, the same engineers who could have spent their time figuring out how to space things out on a screen with margins and padding, instead wasted those precious moments writing CSS support for blinking text. Sigh.
Okay, so HTML e-mail is bad to begin with, but good software developers don't implement stupid stuff until more important things are implemented. Please prioritize what is important. Got it? Cool.