The most-used merge tags:
- `{{clientname}}` — company name
- `{{contactname}}` — first name of the contact person
- `{{firstname}}` — first name (CRM lead)
- `{{lastname}}` — last name
- `{{date}}` — today (long notation)
- `{{invoicenumber}}` — for invoice mail
- `{{meetingdate}}` — for booking mail
- `{{referrallink}}` — affiliate tracking link
- `{{agency_name}}` — name of your agency
The full list is in every template editor under the Variables dropdown — click and it is inserted at the cursor position.