When I went online today, I found myself a member of a Facebook group I was not aware of and, I discovered, not suitable for. I know the group's founder and consider her a friend. I understand that she is eager to promote her business, and wants to build a community of like-minded individuals.
But this is not the way to do it. You don't include people in any social media community without their knowledge and consent, just as you don't include people's emails on your newsletter mailing list without express permission.
It's important to be considerate of everyone's time and attention. Social media, email, and online media demand so much of us, and most people opt in for what they feel they can manage. By all means, invite people to your social media groups. Forward them a sample newsletter. But don't assume that everyone - even friends and family who love you dearly and want to see you succeed - are ready to join your community. Don't put them in the awkward position of having to leave the group. It's inconsiderate and impolite.
And they may not even be suitable members for your particular community. You want participants who are knowledgable and engaged, and who can help support your community. In the case I describe above, I am included in a group for people who like books read aloud via CD or MP3. I actually don't like listening to books read aloud. I vastly prefer podcasts, especially those with a couple of people engaged in lively dialog. I am not even a good candidate for this Facebook group.
So please, remember to ask or invite people to join your online communities. It's the polite thing to do.