def __check_msg_for_headers(self, msg, ** email_headers):
all_headers_found = False<EOL>email_headers['<STR_LIT>'] = email_headers['<STR_LIT>']<EOL>email_headers.pop('<STR_LIT>')<EOL>all_headers_found = all(k in msg.keys() for k in email_headers)<EOL>return all_headers_found<EOL>
Checks an Email.Message object for the headers in email_headers.

Following are acceptable header names: ['Delivered-To',
    'Received', 'Return-Path', 'Received-SPF',
    'Authentication-Results', 'DKIM-Signature',
    'DomainKey-Signature', 'From', 'To', 'Message-ID',
    'Subject', 'MIME-Version', 'Content-Type', 'Date',
    'X-Sendgrid-EID', 'Sender'].

@Params
msg - the Email.message object to check
email_headers - list of headers to check against
@Returns
Boolean whether all the headers were found