"Dear Sirs" and my boiling temper

I received an email at work today regarding some support that they needed. It was addressed, "Dear Sirs." I admit that I make allowances for folks from other countries that might have more…traditional outlooks on the role of women in the workplace. In my experience, they have been taught that "Dear Sirs" is the polite and acceptable way to begin a business letter in english.

This person's name was more English than mine.

Nevertheless, I give the person the benefit of the doubt. I respond with "...