On Tue, Dec 28, 2010 at 01:19:49AM -0800, email builder wrote:
> I might need to learn how to write a milter that tries to divert outgoing
> messages (so a smtp/client milter) that have been sent with
> smtp_tls_security_level = encrypt but failed because the destination server
> doesn't support STARTTLS (I understand that this is something of a false
> flag,
> because even successful TLS message transmission is NOT necessarily secure,
> but
> bear with me if you will).
>
> I haven't yet looked in detail at the milter API, but was wondering if I
> could
> ask two preliminary questions about this:
>
> 1) does the milter API and its placement in the server's execution provide a
> place where I can determine that STARTTLS has failed?
No. Milter processing happens as mail enters the queue, delivery and STARTTLS
success or failure happen when mail is leaving the queue.
> (and where I can manually redirect the message and remove it from normal
> processing) (milter against the STARTTLS command?)
Milters process mail being received, not mail going out.
> 2) does anyone know of a milter that might serve as a good example so I don't
> have to start from scratch?
Outgoing TLS policy failure is a non-milter problem. If you want traffic
that fails mandatory TLS delivery to be re-routed for alternative processing,
you can use a custom transport for mandatory tls:
main.cf:
indexed = ${default_database_type}:${config_directory}/
transport_maps = ${indexed}transport
transport:
example.com tlssmtp
master.cf:
tlssmtp unix - - n - - smtp
-o smtp_tls_security_level=encrypt
-o smtp_fallback_relay=[127.0.0.1]:12345
Note that not all failures will be starttls failures, so the fallback
relay will also receive mail when the remote peer is down, or tempfails
a particular recipient, ...
--
Viktor.
