I'm sure you've already figured this out, but I've found that folks over 50 are pretty much going to call you no matter what. So I would just supplement the mailing list with a business-card size card with your (or whoever the central contact is) phone number on it that you hand to them at a face-to-face meeting. They'll feel better and probably be more amenable to trying the e-mail list.

Finally, for people who are truly beyond the age of e-mail, or have some disability that prevents them from using a computer, you can recommend that they use presto, which is an e-mail service that prints out e-mails sent to the person. My grandmother uses this and the service has made it _so_ much easier to keep in contact with her.

I suspect that you might be doing this for your community disaster plan work -- which is great! -- so I'm sure there are seniors in your neighborhood who will require a little more effort to reach in case of emergency. Presto or the business card with phone number system could probably be good supplements.

Hope this helps!

PS: I've worked with a lot of "seniors" (even taught a few I'net classes at the local senior center) and most of them do quite well ... once they get used to the mouse. ;)

. A quick Google for "maillist" turned up this as the first hit that looked like it might work for you. Lots of others that looked good.
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. Signing up with Google is not very hard nor is it very intrusive. If you have someone to moderate (and a small list), Gmail may work.
. IMNSHO, Google Groups is a PITA to use - not something I'd recommend for newbies.