How to connect a sender for sending email?
This documentation is always evolving. If you've not been here for a while, perhaps check out again this documentation.
To connect a sender to send emails with follow this tutorial.
Click on the "emails" tab in the menu on the left.
Once you are in the email interface, click on "Your senders".
Then click on "Connect a sender".
From the list of senders, choose the one you want to connect.
With Gmail or Google Apps pro the connection is done in 1 click, for other providers, you must enter your SMTP credentials.
Once the sender is added, you can now send emails with your campaigns.