Spintax
Spintax is a text format where each curly-bracket group lists options, and the sender picks one at random for every email.
Spintax lets you write several versions of a phrase in one place. A group like {Hi|Hello|Hey} lists the options, and the sending tool picks one for each email. You can use it for greetings, openers and short phrases.
The aim is to avoid sending thousands of identical messages, because identical bulk content is one of the signals spam filters look for. Spintax helps a little, but it is not a cure. Poor targeting, weak authentication and a bad list will still hurt you, however many versions of a greeting you write.
Keep it small and readable. Too many groups give you broken sentences, mismatched tone or grammar errors that you will never see unless you check. Test every option in a group so each combination makes sense. Preview real output before launch, and avoid spinning the key parts of your offer, because you want to know what people reacted to.
In Terlido
Terlido supports spintax in the form {option a|option b} in email templates and picks one option at random each time it renders an email.