How do you add a simple key to an email?

I have request to add this to my html email in order to indicate a subject line.

For the Subject Lines perhaps you can create a simple key that has the message number and the affiliated subject line.

How would you do this? Thank you.

I think you need to give a bit more information. Would every recipient’s email look different? How are you sending these emails? Are they hand coded or auto-generated?

I can answer those questions. Each email will look different. My client is using a system called Maestro. They are hand-coded. Thanks.

Maestro is evidently a drupal module for automating some business tasks, but from what I read, it’s mostly for credit/debit cards. If you want to learn how to use it effectively, you will need to become familiar with the Drupal documentation

Thank you!!