If you are merging an email sent to multiple recipients, you can include their details in the "recipients" field. This field should have a "to" field with all the recipients from the To: email field. You can include "cc", "bcc", and "from" keys as well, but they're currently not used.
The "recipients.to" field should be an array of recipients, with each entry containing the email address of that recipient, and optionally their name.
The first recipient in this list which matches either the Person ID or one of their relationships will be used for all %contact_*% merge fields. The %contact_rels_first_name% field will return the list of first names.
For example, with the request body above you would get:
- %contact_name% is replaced with "Bob Alvarez"
- %contact_rels_first_name% is replaced with "Bob, Alice and Carol"