I think community leaders should send mass email only when they have big announcements to make or have some interesting offers. I do not think sending summary of activities is a good idea. I have found that not many people are interested in subscribing to your weekly digest.
1) Don’t send to an opt-out unless you have something serious to tell them about. (Worst seem you got data breached and you are required by local law to notify them of such)
2) Digests aren’t particularly interesting, unless it’s curated content they’ve indicated an interest in, e.g, a monthly newsletter of articles from a regular contributing author.
Plus you need to keep in mind, if you over-spam your opted-in users, sometimes they won't complain to you. Instead your emails get marked and stuffed into their spam box.
You want to avoid getting your outbound email addy listed in spamhaus type listing's because then your emails may not even get through the recipients isp as they will pre-identify it as spam and just blackhole them forever.