You can send a message to all the members of a community if the owner has enabled this option, and the community is moderated and has fewer than 1,000 members.

If you don't see the send message link at the bottom of sidebar on the left, or the community has more than 1,000 members, messages will be disabled for all members, including the owner.

As an alternative, you may want to post your message in the community forum with the steps below:

1. Click new topic at the bottom of the forum.
2. Enter a subject and message.
3. Click submit and you're done!