FT_SMTP
==========

SMTP protocol filter.

	Category: 
		Protocol filter

	.. admonition:: **Supported flags**
		:collapsible: closed
		
		FF_READ_ONLY_OUT

		FF_SSL_TLS

		FF_SSL_SELF_SIGNED_CERTIFICATE

	.. admonition:: **Object types**
		:collapsible: closed

		OT_SMTP_MAIL_OUTGOING - outgoing mail

	Indicates object parts: 
		no

The objects contain a mail message in one stream.

When FF_SSL_TLS flag is specified, the library adds FT_SSL filter to a chain automatically after receiving STARTTLS command from mail client.

It is possible to add FT_SSL filter with FF_SSL_TLS_AUTO flag to decode TLS automatically when it starts after the initial plain text handshake.

It makes sense to use FF_READ_ONLY_OUT flag, because the email clients usually have small timeouts, and can break the transfer during filtering a large message in dataAvailable event. If it is necessary to modify/block some outgoing messages, it is possible to return "250 OK" or "554 Transaction failed" status to email client immediately (using OT_RAW_INCOMING object), then retransmit allowed messages via different mail server.

References:
	- http://www.faqs.org/rfcs/rfc788.html