Go to Campaigns and click Create new campaign in the top right corner of the page.
Choose whether you want to create an Audience or a Realtime campaign. Information about the distinction between these types of campaigns found in the documentation.
Once you have created your campaign and filled in the “Campaign setup” and “Target group” sections, go to the Messages section and click Create new message.
Select Email from the dropdown menu. The message setup screen will open.
Under the “Send via integration” heading, select the Mailgun integration that you set up earlier.
Fill in the Sender Information:
“Sender email address” - the address from which the email will be sent
“Reply-to email address” - the address where replies will be sent to
“Sender name” - the name of the message sender.
Create a message template, for which Handlebars may be useful.