I have found that e-mails get 'lost' or 'misplaced' in cyberspace especially to HR departments (not just airlines)
Luckily i have my email client set to save a copy of each sent email, after a few weeks without a response i forward another copy of the email with a small note saying when the first email went through 'just making sure i have the right address...' '...any help would be appreciated...' blah blah blah never had to send a third email.
Though my emails have all been questions. Like how an Australian grade converts to a UK GCSE etc.