I do think it serves a purpose to tell her that one disagrees with her email to the customer, although I agree that it is a shame that it is after the fact, when chiming in before the fact would have served a greater purpose. You know, it is impossible to time responses on CC so that people suggesting one avenue can only get their post up in the same window as people who would have recommended a different avenue. Had I logged on earlier I would have been one of the ones screaming NO DON'T SEND THAT and might have tried to help reshape the wording to something more professional, out of the interest of helping a fellow caker. But I was too late, as were several others. Not that my input would have necessarily been chosen, but it would have hopefully been valuable as another option to consider.
I doubt most of us dissenters harbor any ill will or personal "criticism" against the OP for her email to the customer, but objectively speaking, the email was unprofessional. By voicing our opinion on the matter--even after the fact--we hope that we can help steer her from saying something like that again, and also it serves as a warning that she might anticipate a more hostile communication from the customer as a result.
Also, objecting to the wording can serve as a reminder to all of our fellow CCers that no matter how direct you might want to be and no matter how "right" you may KNOW you are, and no matter how many of your peers at CC may agree with you, diplomacy, tact and detachment will generally get you farther and demonstrate your professionalism far more than the approach used. Of course won't this all be a hoot if the email DID "work" and put the customer in her place?!
I will admit that some customers themselves are impervious to professionally worded correspondence--I've surely read about enough of those around here. So who knows, maybe the attitude of the OP was just what the doctor ordered and perhaps worked after all. It still doesn't make it "professional" though.
You know sometimes we can whup each other on the side of the head when one of us does something dumb like undercharging for a cake or otherwise allowing a customer to walk all over them. It's not always meant to be nasty (I know it sometimes is, I've been here long enough to see THAT too
) but rather to be honest and direct. Again, some here even deliver honesty and directness with unnecessary cruelness, but I definitely don't think that ANYONE who simply
said "That email was completely unprofessional" was being berating or mean.
But that is just MY 2¢!