Maropost offers content tags which allows users to pull in personalized campaign and user data. By using combinations of these tags we can generate and pass unique identifiers (UUID) into the key parameter without the need for any javascript. For example:
{{contact.id}}  pulls in your contact’s unique ID
{{campaign.name}}   pulls in the entire name of your campaign
{{other.time_stamp}}  pulls in the current date and year

Additional custom tags can be created through the Maropost interface. By combining these tags we can successfully create a dynamic UUID and our key parameter would therefore look something like this:
key={{contact.id}}|{{campaign.name}}|{{other.time_stamp}} 

NOTE: the same UUID must always be passed into the key parameter of both the anchor and image tag

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