mail: use hostname for postgres database

Author: daurnimator

mail/files/userdb-aliases.cf

@@ -1,7 +1,6 @@
 # See pgsql_table(5)
 
 domain = hashbang.sh
-# TODO(daurnimator): DNS entry here had to be manually resolved
-hosts = postgresql://mail:[email protected]:25060/userdb?sslmode=require
+hosts = postgresql://mail:userdb-mail-lookup@userdb-attempt-too-do-user-989073-0.db.ondigitalocean.com:25060/userdb?sslmode=require
 dbname = userdb
 query = select name || '@' || host from passwd where name = '%u'