Adding up to two addresses inside of a contact card.
Why would you have two addresses per contact?
One is the Property in question.
The other is the Mailing Address in case it's different and the owner does not live in the residence you are interested in.

Also remember that variables will pull from whatever info you have on REI Blackbook CRM, which means that:

If you're using a custom field in your contacts tab, you must use that custom field as a variable'

For example:
Default is {{FirstName}} and you've edited it and called it FNA1, so variable must be {{FNA1}}.

Your mailer will then look like this:

Dear {{FNA1}}, instead of
Dear {{FirstName}}

*Note:
If you have challenges, please contact: support@reiblackbook.com