Just to clarify:
My friend is not the head admin assistant and the other women aren't secretaries either. She's the Executive Assistant to the Director and also the departmental admin assistant. The other women are program assistants/coordinators who report to their supervisors. The people that are giving my friend work are the bosses of the program assistants because the subordinates don't do a good job. These other bosses outrank my friend because of their position title, but they're not her supervisor. My friend only answers to the division director. But since my friend is also the departmental admin and has that nasty "other duties as assigned" clause in her job description, that's open-ended enough for the other supervisor's to give her extra work under the guise of it being "departmental related." It's not really because they have subordinates to do these projects.
The initial email was written not by my friend, but by another coworker who wanted to stop eating lunch with the women in the clique. They still don't talk to her much aside from work related issues. I'm not too involved with the women in the clique, I am on speaking terms with them, but my actions have indicated that I don't want to be included in their little group and they leave me alone. Also, I'm not in that department which helps.
Thanks for the advice FineLine, I like the idea of sandbagging. The other women are definitely doing this since they know someone else will pick up their slack. As far as the work load situation is concerned, my friend accepts that some of the blame lies with her, so now it's just a matter of taking a course of action that will make her duties manageable.
I think I'm going to start a thread about alpha females when my thoughts are gathered enough on the matter. Alpha females are this strange mix of outright aggression, passive-aggressiveness, sugar, battery acid, and vulnerability all sandwiched together.