If set to true, and the server supports the 8BITMIME extension, text
parts of this message that use the "quoted-printable" or "base64"
encodings are converted to use "8bit" encoding if they follow the
RFC 2045 rules for 8bit text.
If set to true, and this message has some valid and some invalid
addresses, send the message anyway, reporting the partial failure with
a SendFailedException.
This class is a specialization of the MimeMessage class that allows
you to specify various SMTP options and parameters that will be
used when this message is sent over SMTP.