Email body mistakenly treated as headers if first body line contains colon

[thomasst]

Since "Timezone:" looks like a header, quotequail treats it as such, but shouldn't.

        body = [
            'Begin forwarded message:',
            '',
            'From: %s <%s>' % (user.full_name, user.email),
            'To: x@example.com',
            'Subject: New customer',
            '',
            'Timezone: %s' % user.get('timezone'),
            'Team Name: %s' % name,
            'Plan: %s' % plan,
            'Phone number: %s' % phone_number
        ]
        body = '\n'.join(body)

via https://help.close.io/agent/case/21570