Changes for version 1.939 - 2017-01-14 (TRIAL RELEASE)
do not decode MIME headers known to be never encoded (Pali Rohár)
...and that includes the Downgraded-* headers (Pali Rohár)
Changes for version 1.938 - 2017-01-01 (TRIAL RELEASE)
numerous small fixes to header encoding (thanks, Pali Rohár) for more details see https://github.com/rjbs/Email-MIME/pull/32
When a single-part content type has been provided with multiple parts, the user is now warned that the type has been changed to multipart/mixed. This helps catch typos like "mutlipart/alternative".