john the ripper on crypt passwords out of postfixadmin

This might help my future self :

SELECT username, password into outfile '/tmp/passwords.txt' fields terminated by ':' optionally enclosed by '' lines terminated by '\n' from mailbox where mailbox.active = 1;

and then :

john /tmp/passwords.txt ….

e.g.

root@mail:~# john /tmp/passwords.txt 
Created directory: /root/.john
Loaded 2327 password hashes with 2326 different salts (md5crypt [MD5 32/64 X2])
Press 'q' or Ctrl-C to abort, almost any other key for status
(vulnerablePassword) whoopsy@example.com