QBitFramework/QBit-Application-Model-SendMail — pull request #2 by wtertius (2013-10-31 12:14:24+00:00)
Title: Do not warn on empty headers.

Often and often fields cc, bcc and source_spot are empty. Indeed they
have undef value. When new MIME object is created it warns about
undefined value in string concatenation.
This commit resolves the described problem.