Microsoft Program Manager interview questions

Got the interview through a recruiter. It was a 30 minute on campus interview. 1.Design an e-mail system. Didn't actually have to code anything just had to explain how I would go about doing this. 2. How would you remove duplicates from a singly linked list 3. Add two integers without using the add operator

Lasted only about 40 minutes. Outside of the typical "Why should we hire you", "What was the most difficult technical problem you have had to deal with" questions, the main brain teaser question was this: Prove that this sentence "A man, a plan, a canal: Panama" is a palindrome using code. They also had a couple of questions continue off of that one such as how would you break the code.