Parece que você está procurando pelo? opção:
? (question mark): The hotstring will be triggered even when it is inside another word; that is, when the character typed immediately before it is alphanumeric. For example, if :?:al::airline is a hotstring, typing "practical " would produce "practicairline ". Use ?0 to turn this option back off.
Então, assim:
:*?:''m::@mailinator.com