Customer Personalization by gender

I want to address our customers according to their gender:

Our customers are sorted by gender (we are using the Shopify App Customer Gender), so every customer in Shopify is linked to a female or male tag. What do we need to do that we can address women and men with a different salutation?

Dear (Mr. or Mrs. - depending on male or female tag) {{ last_name|default:'friend' }}

Example if a customer has the male tag: Dear Mr. xy
If a customer has a female tag: Dear Mrs. xy

Thanks in advance!