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 a single stream.
When the FF_SSL_TLS flag is specified, the library automatically adds the FT_SSL filter to the chain after receiving the STARTTLS command from the mail client.
It is possible to add the FT_SSL filter with the FF_SSL_TLS_AUTO flag to decode TLS automatically when it starts after the initial plain-text handshake.
It makes sense to use the FF_READ_ONLY_OUT flag because email clients usually have short timeouts and can break the transfer when filtering a large message in the dataAvailable event. If it is necessary to modify/block some outgoing messages, it is possible to immediately return the “250 OK” or “554 Transaction failed” status to the email client (using an OT_RAW_INCOMING object), then retransmit allowed messages via a different mail server.
- References: