Treat the earth well: it was not given to you by your parents, it was loaned to you by your children. We do not inherit the Earth from our Ancestors, we borrow it from our Children. ~ Ancient American Indian Proverb
Contacts and groups are routinely intermingled in a standard MS Exchange contact list. How you personally have your contact list set up is irrelevant.
It is not uncommon for people to be in a hurry and accidentally click on the wrong contact. I saw it happen at one of my companies just last week where an attorney clicked on the contact above the one he really wanted to send to. This resulted in sending confidential internal case documents to the opposing council. It happens. Are you going to sit there and tell me that this attorney was secretly sympathetic to the opposing lawyers and that's why he sent that email message?
You cannot ascribe motive or beliefs to a person based on a mistakenly sent e-mail message. I have forwarded e-mail to friends based on both agreement and on strong disagreement. I have printed out some of the comments here that I strongly disagree with so as to ridicule those statements to others. Because I printed out a statement by Lerxst suddenly means I agree with his statements? Again, horse crap!