Features:
* #804 - Configurable SMTP open_timeout and read_timeout. (ankane)
* #853 - `Mail::Message#set_sort_order` overrides the default message part sort order. (rafbm)
* #650 - UTF-7 charset support. (johngrimes)
* #1065 - Require STARTTLS using :enable_starttls. (bk2204)
* #1002 - Transcoding replaces invalid chars with "�" instead of discarding them. (kjg)
* #1094 - Core extensions removal: Drop `String#at`, `from`, `last` and `is_utf8?` since they are no longer used by Mail internals. (metcalf)
* #1095 - Core extensions removal: Drop `String#mb_chars`, `not_ascii_only?`, `constantize`, `first`, `to` to avoid monkey patching the standard library. (metcalf)
Performance:
* #1059 - Switch from mime-types to mini_mime for a much smaller memory footprint. (SamSaffron)
Compatibility:
* #464 - Improve attachment filename detection by preferring Content-Disposition filename. (lawrencepit)
* #655 - Sort attachments to the end of the parts list to work around email clients that may mistake a text attachment for the message body. (npickens)
* #982 – Faithfully preserve unfolded whitespace rather than collapsing to a single space. (jeremy)
Bugs:
* #539 - Fix that whitespace-only continued headers would be incorrectly parsed as the break between headers and body. (ConradIrwin)
* #876 - Strip valid RFC-1342 separator characters between non-matching encoded-words (Caleb W. Corliss)
* #978 - Fix for invalid chars being left in a string for invalid b_value from encoding. (kjg)
* #996 - Fix that multipart/mixed emails with a delivery-status part could be interpreted as bounces. (kjg)
* #998 - Fix header parameter parsing (such as attachment names) for values encoded with a blank charset or language code. (kjg)
* #1000 - Fix header parameter parsing (such as attachment names) to transcode to UTF-8 (kjg)
* #1020 - Don't set SMTP verify mode to nil when config was not provided. (jhass)
* #1032 - Fix that comparing messages changed their raw Message-ID to their parsed message_id. (bobjflong)
* #1074 - Fix that the first address in a list is dropped when a subsequent address has non-US-ASCII characters. (domininik)
