Here are variable to customize your eMails to your clients. Currently there is a different set for Autoresponders and Broadcasts.
Common Broadcast Variables
${fname}
${lname}
${email}
${unsubscribe}
Common Autoresponder Variables
${contact.fname}
${contact.lname}
${contact.email}
${unsubscribe}
Please let me know if you want or need any other variables.