Including code examples of what you have down or what you are trying to do can make it easier for people to understand your request.
Each (fake) email is a variable.
I am uncertain what you mean by this statement, do you mean that each "fake email" value is assigned to its own variable...
<<set $emailA to "Some value that represents a fake email">>
<<set $emailB to "Some value that represents a second fake email">>
<<set $emailC to "Some value that represents a third fake email">>
... or do you mean something else?
Anyway, the following code demonstrates how to initialise a variable to an empty Array, and how to later add three new values to that Array.
/% Initialise the sent variable to an empty Array. %/
<<set $sent to >>
/% Add three String values to the sent Array. %/