I post my monthly Wine Events Calendar to my other wine blog, at http://mcwong1946.blogspot.com/ (you should subscribe to that too), and send it out to the 35 or so members of my winetasting group, and also post links to Twitter to the hundred or so people, many following me because of wine things. It's hard to tell how much action my efforts generate.
In the areas where I can see action, it's discouraging. From my winetasting group, for example -- only one couple I recognized showed up with me at the Oakland Urban Wineries event. (More may have come from the blog or Twitter, but I don't have an easy way to determine that since I don't know any of them on sight.) More directly, I tried setting up a visit to a winery with the winetasting group, and of the 50 members, none responded. I'm setting up a wine-and-chocolate-tutorial and had to message each person individually, one by one, to get an RSVP! (Fifteen have responded in the affirmative, but only after I messaged each one!)
Regarding the winetasting group, I've decided that you just can't expand an existing group into broader participation. Our group goes to our monthly tasting event. Period. Trying to let them know about other events, and let's get together, or let me know if you're going too so we can link up -- nope. One monthly winetasting. That's it.
So I've decided that I won't try to broaden that group's charter. They are there for one thing; leave 'em alone.
Instead, I've sent emails to members of the group (again, one by one) inviting them to join my separate mailing list on Art events (openings, shows, and art classes). Six couples have responded affirmatively. That's good. It's a start, anyway.
Next, I will query my wine group and ask who wants to be on the list to get a full wine-events monthly calendar. For the ones who say no, or who fail to reply (most people simply don't reply to anything), I will trim down my monthly newsletter to just info about the club tasting that just passed, and the club tasting coming up next. More is a complete waste. Email lurkers don't appear to have any longterm value -- I've never gotten growing participation over time from just sending emails.
I also get members asking me to forward email queries or alerts about things you'd think would interest members of the group. I will decline hereafter; they have access to the list, they can send if they like, though it will be largely bootless for them to do so.
This is why it is critical to grow your group as large as you possibly can. If only one percent will respond to any given opportunity, you need lots of subscribers or Followers to have any impact at all. Or at least, to have any impact worth the effort you put into it.