Eg1: Prospect name - Muneesh Tyagi
Syntax: {{#if firstname}}{{#endif}}
Usage: Hi {{#if firstname}}{{firstname}}{{#endif}}
Output: Hi Muneesh

Eg2: Prospect name - Muneesh
Syntax: {{#unless lastname}}{{#else}}{{#endunless}}
Usage:  Hi {{#unless lastname}} there, {{#else}} {{lastname}} {{#endunless}}
Output: Hi there,

Eg3: Considering today is Thursday.
Syntax: {{#if is_thursday}} and  {{n_days_fromnow}}
Usage: {{#if is_thursday}} Hey, would you be available for a meeting on {{4_days_fromnow}} {{#endif}}.
Output: Hey, would you be available for a meeting on Monday. 

Eg4:
Syntax: {{n_years_fromnow}}
Usage: Hey would you be interested in for a demo in the year {{1_years_fromnow}} sometime?  
Output: Hey would you be interested in for a demo in the year 2020 sometime?  
Same way it works for months, days and weekdays once put in the values. 

Eg5: Prospect Name: Muneesh
Syntax: {{n_years_ago}}
Usage:
Hey {{firstname}},
Hope you remember me, we had a conversation over a call in {{2_years_ago}} in regards to..
Output:
Hey Muneesh,
Hope you remember me, we had a conversation over a call in 2017 in regards to..
Same way it works for months, days and weekdays once put in the values. 

Just to make sure your variables are set as desired you can check the preview of the mail as shown in the screen below:

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