DEAR MISS MANNERS: I have an account on a business-oriented social media website. I set up the account for professional reasons; however, I rarely visit the site. I accepted invitations to connect without any vetting, and now have a couple thousand “connections.” As a result, I now get a lot of unsolicited direct messages inviting me to connect and discuss the sender’s services. Even though they are sent to me directly, and often have some sort of personalized touch, do I have an obligation to respond? I view unsolicited emails akin to unwanted marketing calls and tend to ignore them. What is …