Changes for version 0.79_16
- experimental SMTP AUTH support (LOGIN PLAIN CRAM-MD5 DIGEST-MD5)
- Fix bug where one refused RCPT TO: would abort everything
- send EHLO, and parse response (for later AUTH implementation)
- better handling of multi-line responses, and better error-messages
- Also normalize line endings in headers
- Now keeps the Sender header if it was used. Previous versions only used it for the MAIL FROM: command and deleted it.
- No space between "MAIL FROM:" or "RCPT TO:" and address.