Twilio SendGrid provides tools for creating marketing campaigns, including single sends, to send emails to contacts with customizable subject lines and preheaders. To create a single send, navigate to the "Single Sends" section in the SendGrid dashboard and click on "Create a Single Send". The design editor allows for configuration of email appearance and entry of relevant information such as sender details and contact lists. Before sending an email, a sender must be created with verified domain information and contacts added to receive the email. Once confirmed, the email can be sent to selected contacts and reviewed before hitting send. Twilio SendGrid's A/B testing resources are also available for future campaign versions.