Subject encoding problem

[tsvetckovdmitriy]

Problem: There is a problem when parsing the message header, sender and recipient.

Description:
I send messages using the library from Microsoft SmtpClient. The library has a feature where the Base64-encoded character code breaks into multiple lines. Microsoft forums

Example

begin
	mail = Mail.new
	mail.to = '=?utf-8?B?WFhYWFhYWCAtIDUgcGVyc29ubmVzIHZvdXMgb250IG5vbW3D?= =?utf-8?B?qSBndWlkZQ==?='
	mail.from = '=?utf-8?B?WFhYWFhYWCAtIDUgcGVyc29ubmVzIHZvdXMgb250IG5vbW3D?= =?utf-8?B?qSBndWlkZQ==?='
	mail.subject = '=?utf-8?B?WFhYWFhYWCAtIDUgcGVyc29ubmVzIHZvdXMgb250IG5vbW3D?= =?utf-8?B?qSBndWlkZQ==?='
	puts mail.to
	puts mail.from
	puts mail.subject
end

Expected result:
XXXXXXX - 5 personnes vous ont nommé guide
XXXXXXX - 5 personnes vous ont nommé guide
XXXXXXX - 5 personnes vous ont nommé guide

Actual result:
XXXXXXX - 5 personnes vous ont nomm�� guide
XXXXXXX - 5 personnes vous ont nomm�� guide
XXXXXXX - 5 personnes vous ont nomm�� guide

In spite of this defect most of mail services can recognize these headers without problems. Can you fix this problem in this library?