Logging when proxying SMTP / IMAP / POP sessions

[Maxim Dounin]

Hello!

On Tue, Jan 16, 2018 at 12:23:31PM -0800, Luis E. Muñoz wrote:

[...]

> Proxying and authentication works as advertised, no issues. However, 
> I've been unable to locate any piece of documentation indicating how to 
> produce a suitable access log message (ie, a log tying the mail client 
> with the backend server its connection was sent to). I've tried the 
> `access_log` / `error_log` directives at various places in the 
> configuration, to no avail.
> 
> HTTP/HTTPS logging works as usual.
> 
> Given how I've not seen any mention to logging in the various documents 
> that describe SMTP/IMAP/POP proxying, I believe the functionality for 
> this does not currently exist. This logging is very important for 
> troubleshooting and support.
> 
> Is there something I'm overlooking? If indeed the functionality doesn't 
> exist, would it be possible for me to write and contribute the code 
> required to add said logging?

The error_log directive as available in the core module works for 
mail module, too.  If needed, you can set a specific error log in 
mail{} or server{} contexts.  See http://nginx.org/r/error_log for 
details.

There is no access log support for mail.  Instead, basic mail 
session events are logged to the error log at the "info" level.

-- 
Maxim Dounin
http://mdounin.ru/