When a supporter signs a petition, takes a pledge, or donates to a fundraiser you post, they will automatically join your campaign and be subscribed to receive any action you send via email. Some supporters may not wish to receive your emails and have the option of unsubscribing to your emails, which is why the number of supporters you have may not be the same as the number of emails that are sent.
You can view the number of supporters your campaign has gathered on the right side of your campaign page. If you'd like to increase the number of subscribers you have, read our tips on posting successful actions. The more actions that people take through your campaign, the more reach you'll have with future campaigns.