Blueshift uses liquid to personalise emails:

#{{user.name}}

You can read more here: https://help.blueshift.com/hc/en-us/articles/115002708213-Personalization-using-Liquid

These can be set up in the personalisation settings in Taxi.

These will become available in rich text fields in the editor.

You can add as much or as little code here as you like, so it’s possible to use liquid to do things like use a default name:

{% if user.firstname == blank %}{% else %}#{{user.firstname}}{% endif %}