Closed Issue: FormatException when message headers contain multiple entries for Content-Type [1839]

* 159 FETCH (UID 176 FLAGS (\Seen INBOX.enviadas) BODY[HEADER.FIELDS (FROM TO DATE SUBJECT CC CONTENT-TYPE)] {307}
Date: 06-12-2013 10:14:49
From: Suport <--------@--------.com>
To: suport@--------.com <--------@--------.com>
Subject: Fwd: RES: -------------------------------------------
Content-Type: multipart/mixed;boundary="part000"
Content-Type: text/plain; charset=utf-8

BODYSTRUCTURE (("text" "html" ("charset" "utf-8") NIL NIL "base64" 8500 0 NIL NIL NIL NIL) "mixed" ("boundary" "part000") NIL NIL NIL))
IMAPX180 OK Fetch completed.
A first chance exception of type 'System.FormatException' occurred in System.dll