Having a big mailing list isn’t as important as having the right mailing list. Normally, you also want to make sure that you’re making the most of the emails you send.
Earlier this year I started getting mail from the Australian Christian Lobby. (I’m not sure how they got my details.) ACL was sending me identital emails each week, and every now and then a letter that said almost the same thing. (I personally think this is part of a strategy to promote fear among more fearful Christians, particularly in relation to the Safe Schools program.) I emailed them back a couple of times to discuss the subject of the email, but I didn’t hear back. (I found a while back that they’d blocked me on Facebook, so no opportunity for conversation there.) I ended up unsubscribing from their email list because I don’t need their repetetive emails clogging up my inbox. A few days ago I emailed them asking to be taken off their postal mailing list too, but I haven’t heard back. Hopefully they get that it’s wasteful mailing people who haven’t signed up.