The SMTP transport sends emails using the SMTP protocol.
This SMTP client follows RFC 5321, and is designed to efficiently send emails from an application to a relay email server, as it relies as much as possible on the relay server for sanity and RFC compliance checks.
It implements the following extensions:
Provides limited SASL authentication mechanisms
Error and result type for SMTP clients
SMTP response, containing a mandatory return code and an optional text message
Utils for string manipulation
Contains client configuration
Structure that implements the high level SMTP client
How to apply TLS to a client connection
Configures connection reuse behavior
Default smtp port
Default submission over TLS port
Default submission port