Getting more visitors isn't the biggest problem (besides the possible bandwidth problem leading to more costs, leading to more adverts...). There is another problem. How are you going to contact more that 20000 people and ask them if they are interested in a newsletter? Posting the question in the forum is no option since many don't use the forum (see the reaction to this thread). Having the option when you register is good but would only be seen by new members. Putting the option in Profile will also only be seen by the regulars here.

The only(?) option you have is to send every registered member, who doesn't visit very often, an e-mail asking if they are interested in the newsletter. Now can you spell SPAM?

Just to keep the discussion going,

Crash