Query: You and multiple co-contributors need to keep a hundred or more people up to date while maintaining your sanity and keeping costs low. Is this possible?
In short yes. There are a plethora of options you could go with from freemium (unlock more features with a paid account) to corporate CRM solutions (low on sanity but high on capability). I'll focus on the free to low-cost options here. First things first though, identifying your wants and needs. Do you want other members of the group able to talk to each other within a group setting? If so then a forum or blog may be the option for you. If you'd rather your groups be disconnected from the group setting then a Newsletter may be the way to go.
Easy to do/maintain.
Can be free via many website hosting services.
Availible to everyone or you can put the blog behind a membership.
Commenting on posts can be turned on or off at your leisure. You could also moderate the comments so that you see each comment before it is allowed on to the site.
You have limited control over who sees the blog. You can limit it by a membership wall, but it's up to the audience to go and look.
Simple format makes finding past information somewhat more challenging.
Free websites don't include a custom domain name and include host branding (some more than others).
Multiple admins can be assigned and each can post topics and moderate the group.
A private section for just adims can be utilized to keep the admins up to date without cluttering inboxes and new admins can see past posts.
Robust structure allows for a community to grow and keep up to date with each other with ease.
Users can interact with each other, not only with comments on posts, but with post of their own.
Access can be set anywhere from only members can see or comment on the posts to anybody can see and comment on the posts.
Can be done entirely free.
Moderating the forums can be a tricky tight rope to walk. Keeping the balance between respecting freedom of speech and keeping conversations civil can be difficult.
Free version doen't allow for a custom domain and has some minimial branding.
Email Marketing Solutions
Examples include MailChimp, Zoho Campaigns, or HubSpot.
Multiple users can login and add recipients for different mailing lists keeping those mailing lists up to date for all users.
Email large quantities of people a newsletter while maintaining consistency across all emails.
Can be done free up to a certain number of recipients.
No community interaction.
Email addresses may have to be manually entered.