Motivation:
If the remote server returns a 4xx/5xx error in response to
a DATA command (or earlier command if using pipelining),
SmtpRequestEncoder can become stuck in an invalid state,
not allowing any requests to be sent.
This makes the channel unusable and the connection has to be closed,
or the encoder handler has to be replaced.
Modifications:
If a RSET command is written to the channel, the contentExpected
flag is set to false, and the RSET is written to the channel.
Result:
Sending a RSET command after a server 4xx/5xx error will make it
possible to use the current connection for new mail transactions.
Motivation:
When writing a SMTP client a provided SMTP codec that follows RFC2821 is useful.
Modification:
Add client side codec and test.
Results:
People who want to write a SMTP client can reuse the codec.