FT_SMTP

SMTP protocol filter.

Category: Protocol filter

Supported flags:
FF_READ_ONLY_OUT
FF_SSL_TLS
FF_SSL_SELF_SIGNED_CERTIFICATE

Object types:
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 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