“Designed” e-mail is just a slightly more polished version of those messages your uncle sends you. Your uncle thinks 18pt bright red Comic Sans looks great, so he sends e-mail messages formatted that way. You cluck your tongue, or sigh, or run de-formatting scripts on every message you receive from him. When your uncle is the “designer,” you “get” why styled mail sucks. It sucks just as much when you design it, even if it looks better than your uncle’s work in the two e-mail programs that support it correctly.
Couldn’t agree more.