virtaul domain:
user = mail
password = mypass
dbname = mail
query = SELECT domain AS virtual FROM domains WHERE domain='%s'
hosts = 127.0.0.1

email2email:
user = mail
password = mypass
dbname = mail
query = SELECT email FROM users WHERE email='%s'
hosts = 127.0.0.1

virtual forwardings
user = mail
password = mypass
dbname = mail
query = SELECT destination FROM forwardings WHERE source='%s'
hosts = 127.0.0.1

virtual mailboxes:
user = mail
password = mypass
dbname = mail
query = SELECT CONCAT(SUBSTRING_INDEX(email,'@',-1),'/',SUBSTRING_INDEX(email,'@',1),'/') FROM users WHERE email='%s'
hosts = 127.0.0.1