Said Bachiri you could do this by adding another filter into your smart list that says "email address is not: xyz@abc.com"
Otherwise, you're sort of defeating the purpose of a smart list which is intended to be dynamic and always representative of your database at a point in time.
This is defeating the purpose of a smart list and would introduce very significant risks of errors, as one would not remember after a while that a given lead has been removed.
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