The SMTP filter API provides services for accessing SMTP messages processed by the WinGate SMTP server. You access and modify SMTP messages and data as they progress through the SMTP chain.

Message Filtering

You register an SMTP filter with a call to SMTPFilterRegisterFilter. In this call you provide a SMTPFilterProviderInterface for the framework to call you to process commands, responses, data and manage lifetime management of your filter.

Sending Messages

The API also provides functions for sending SMTP responses and messages via SMTPFilterSendResponse and SMTPFilterProcessMessage. You can also send commands by setting SMTP context and calling SMTPFilterProcessCommand