e-mails not in multiple tables
SELECT email FROM tvp_2012
WHERE email NOT IN (SELECT ppl_email FROM tvp_2016)
UNION
SELECT email FROM tvp_2013
WHERE email NOT IN (SELECT ppl_email FROM tvp_2016)
UNION
SELECT insc_email FROM tvp_2014
WHERE insc_email NOT IN (SELECT ppl_email FROM tvp_2016)
UNION
SELECT ppl_email FROM tvp_2015
WHERE ppl_email NOT IN (SELECT ppl_email FROM tvp_2016)
ORDER BY `email` ASC