This should work, I believe:

SELECT * FROM table WHERE MONTH(date_of_birth) = MONTH(CURDATE()) AND DAY(date_of_birth) = DAY(CURDATE()) AND email NOT NULL AND email !='';

Edit for less processing overhead:

SELECT * FROM table WHERE DATEFORMAT(date_of_birth, '%c %e') = DATEFORMAT(CURDATE(), '%c %e') AND email NOT NULL AND email !='';

You could go even easier, if there is a large database, and replace the second DATEFORMAT() with a PHP variable containing the current date and month, separated by a space.

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