Anonymity

I guess this is a question to other pastors out there... or I guess anyone in a leadership position.

How do you feel about letters written to you from an anonymous person?  I opened a letter the other day which started "Regarding your sermon last week..." - I stopped reading at that point and looked at the end of the letter... which was not signed with a name.  I chose not to read the rest.  For one I knew that no matter what was said in the letter (either good or bad) that I had no opportunity to respond to the writer. Knowing the way my mind works I knew I'd spend time formulating responses in my head, so with no output I decided to give myself no input on the matter either.

But it left me wondering if I handled it correctly.  I know at college many of the lecturers said they didn't open or read anonymous letters - in a way I thought they sounded a little arrogant, but when faced with the position myself I acted the same way.  Do people deserve the right to anonymity, or should we only respond to those who can stand behind their statements?  A little pastoral input would be good on this...