Marketing emails often don't contain links, which kind of defeats the purpose. Even more troubling in my opinion is the number of pitch emails I get that don't contain links. I like to link out to stuff since, more than anything, it bestows a kind of legitimacy to what I write. If I get a press release that's just been pasted into an email I more or less ignore it since it gives my readers nowhere to turn for more info.
Everyday I receive an email newsletter from Potomac Tech Wire which consists entirely of press releases with links. It seems they won’t pick up a release unless it is linked.