I sometimes use e-mail if I changed my forum theme, or have important news to share with members, but now I mostly use Facebook, Twitter, YouTube, and other social networks to promote my forum and blogs on a regular basis.
My forums were usually about a video game, so I usually used the mass email when there was news about said game, or if I had an idea to help out sales of that game.
I actually used the mass email to say that I was merging my three forums into one on a brand new forum.... only one person came from that email out of like 300
But.... It's the thought that counts? XD
I think if you were on the internet in the early days like 1995 or sooner, and you built-up a huge list with 1000s of e-mail subscribers, I think it will still be useful.
I use e-mail to promote my blog by sending them notifications when I post new post, and I sometimes mass e-mail members on forum, and get a response.
e-mail could be the most stable form of traffic if you engage your readers, and keep them coming to your site for more cool news since e-mail does not change as much as search rankings which change everyday.
Plus, social networks sometimes come and go when newer better networks come out like Myspace, Bebo, and Orkut, are no longer as popular these days because almost everyone I know moved on in using Facebook and Twitter.
