To send a bulk email or SMS to all candidates in a particular talent community, select "Talent Communities" from the main menu and click on the name of the community you want to email / SMS
Add all of the search results to a list
Then give your list a name and click "Add"
From there, head to "Com Campaigns" from the main menu and select either "New Email Campaign" or "New SMS Campaign" depending on what you want to do
Fill in "Step 1" on the next screen with the details of your email
Then in step 2 click the "+Add Recipients" button and select select "From Existing lists"
Pick the list you just created and click "Update"
Launch the campaign