If a specified custom field contains any value, display some content.
[if:CustomField]Your content here[endif]
To display content to subscribers who have no value in the specified custom field, use:
[if:CustomField][else]Your content here[endif]
thankQ Example:
Field Rule for Last Donation – PARAMATERVALUE24 could be used to insert certain text if the contact has donated or on the other hand, not donated.
[if:PARAMETERVALUE24] Thank you for your last donation of $[PARAMETERVALUE24]. [else] Please click on Donate and help our cause[endif]