# Turn on debug mode in Postfix

There're few ways to turn on debug mode in Postfix, you can choose the one you prefer.

## Verbose logging for specific SMTP connections

To debug smtp connection from particular client or sender server, list client hostname or IP address in the `debug_peer_list` parameter (in `/etc/postfix/main.cf`). For example:

    debug_peer_list = 192.168.0.1

You can specify one or more hosts, domains, addresses or net/masks. Execute command `postfix reload` to make the change effective immediately.

## Making Postfix daemon programs more verbose

There're many daemon services defined in `/etc/postfix/master.cf`, for example:

    smtp      inet  n       -       n       -       -       smtpd

To make Postfix logging verbose info of this daemon, please append one or more `-v` options to selected daemon and execute command `postfix reload`.

    smtp      inet  n       -       n       -       -       smtpd -v

- To diagnose problems with address rewriting specify a `-v` option for the `cleanup(8)` and/or `trivial-rewrite(8)` daemon.
- To diagnose problems with mail delivery specify a `-v` option for the `qmgr(8)` or `oqmgr(8)` queue manager, or for the `lmtp(8)`, `local(8)`, `pipe(8)`, `smtp(8)`, or `virtual(8)` delivery agent.

## See also

- Postfix Debugging Howto