How Do I Add New Contacts from a Group to a Campaign?

There's An Easy Way to Subscribe Contacts Just Added to a Group, to a Campaign

If you add new contacts to a group, you also will need to add them to a campaign. Adding a new contact to a group does not automatically subscribe them to a campaign. We do this on purpose, so your new contacts aren't getting blasted with a ton of emails the group already received!

You will need to add the contact to a group and then go to My Content > My Campaigns and locate the campaign you want to add these new contacts to by clicking "Manage Groups" under the "Actions" column:

Then, click the plus button for the group you just updated. Those new contacts you added can then be subscribed to this group:

They will receive the first email in the campaign within an hour!