SELECT DISTINCT EMAIL FROM (
SELECT T1.EMAIL FROM TABELLA1 T1 JOIN TABELLA2 T2 ON T1.EMAIL=T2.EMAIL
UNION
SELECT T1.EMAIL FROM TABELLA1 T1 JOIN TABELLA3 T3 ON T1.EMAIL=T3.EMAIL
UNION
SELECT T1.EMAIL FROM TABELLA1 T1 JOIN TABELLA4 T4 ON T1.EMAIL=T4.EMAIL
) T0

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