Template variable

A template variable is a placeholder in a template that is replaced with a value for each recipient when the message is rendered — a first name, a plan name, an order total, an expiry date. Other tools call the same thing a merge field or a merge tag.

Variables are what make one template into a hundred thousand personalised messages, and they are the reason a template is worth having at all rather than assembling markup in your application.

Two failure modes worth designing for

A missing value. If half your contacts have no first name, Hi {{first_name}}, renders as Hi , for them. Decide what an absent value should produce before you send, not after — a sensible default is usually better than an awkward greeting.

Untrusted content. A variable whose value came from a user is content you did not write, rendered into markup. Sendly escapes variable values at the render boundary so a value cannot inject markup into the message, but the general principle is worth carrying into your own templates too.

In Sendly

Templates are a reusable object with their own API, and a variable's value comes from the contact's fields or from data supplied with the send. A template may also supply the From address, which is why the send receipt reports the sender actually used rather than assuming it was the one you passed.

Sandbox test sends let you check a render against real data without mailing anyone.

See Templates.