"Thank you" notes after giving a seminar talk I am just finishing my PhD and I have now been on the job market and started to speak at many universities. I have realized it is a time commitment for a person to host a seminar speaker and am really grateful for the experiences that many of my hosts have given me at these universities. For this reason, I have made a policy of sending thank you notes to those that host me when I visit another university's seminar.  These notes that I write typically just say thank you for taking time to host me and funding my visit (if they funded it). It also thanks them for their input and questions about my work if they gave me a useful idea. One of my colleagues has told me this is odd, so I wanted to ask:

Is writing thank you notes to someone for inviting me to speak and hosting me at their university overkill? Is there any negative outcome that can happen from doing this?
I agree that sending a paper thank-you note is a little unusual.  There's nothing wrong with it, of course.  You may come across as slightly eccentric, but academia has plenty of people like that!

A thank-you email, on the other hand, is perfectly usual.