You can use the S1 tag to enter any of the constituent's personalized information. 
Manually type the appropriate s-tag in the HTML editor of the email message.

For formal salutation maually type, [[S1:Salutation_Formal]]

Standard

    [[S1:attribute identifier]] or [[S1:special identifier]]

    XML

    <convio:session name="1" param="attribute identifier" />

For a less formal message, you can also render the recipient's first name using the S1 tag

For example manually type, [[S1:first_name]]

The example above will render the first name of whoever is viewing the greeting

For more information about S-tags, see our documentation on What are S-tags?