To CFI.. You said - "Resumes addressed to Dear Sir, don't get very far with me." Did I read that correctly or are you merely playing heavy handed humourist?
One presumes that the hapless applicant seeking a job at your organization would not know if you were a Miss, Mrs, MZZ, or even a Madame. Perhaps you are even prefer the imposing title Dear Captain? Many GA managers love that title and wear 4 bars to prove it.
Come of the grass CFI. The poor sod that is forced to look for a job with you has probably written a hundred Dear Sir letters. So he took a punt this time and got the gender wrong. Big deal. Is that so important to your ego that you would trash his application? I can't believe this.