---

SELECT
    n.nspname AS schema_name,
    p.proname AS function_name,
    p.oid::regprocedure AS signature
FROM pg_proc p
JOIN pg_namespace n
    ON n.oid = p.pronamespace
WHERE position(
          'mail.api_new_message_group('
          in lower(p.prosrc)
      ) > 0
  AND NOT (
      n.nspname = 'mail'
      AND p.proname = 'api_new_message_group'
  )
ORDER BY n.nspname, p.proname;