What are merge tags and how are they used?

Merge tags (also known as variables or personalization tags) are used to serve unique ads to each user and direct them to the correct ad landing page

There are two key merge tags in each of our ad URLs that need to be replaced for each user and email send:
  1. The merge tag for the email recipient's email address
    1. must work inside an image URL
    2. must work inside a click URL (it is usually the same)
  2. The merge tag for a value that is unique to each send. ESPs often support a campaign ID or time-stamp.
    1. optional—not all ESPs support this merge tag
    2. must work inside an image URL
    3. must work inside a click URL (it is usually the same)

We support the raw subscriber email address as well as unsalted MD5 out of the box. Other hashing mechanisms or unique IDs will work but we will not be able to correlate the users with existing data in our system, reducing performance optimization opportunities. For privacy reasons we do not store the email address or other hash that is passed to us.

In order of best to worse for performance and revenue:

  1. Unique email address
  2. Unique unsalted MD5
  3. Unique unsalted SHA1/SHA256
  4. Unique salted hash or opaque ID (discouraged as we will not be able to match users across the network)
  5. Unique per-newsletter opaque ID (discouraged as we will not be able to match users across the same company newsletters or across the network)
  6. Unique per-send opaque ID (strongly discouraged as we will not be able to recognize users between sends, with all users being seen as new every send, potentially seeing the same ads again and resulting in degraded performance)