We had an alumnus come talk about his job in one of my classes. I already have a job lined up, but think he's a pretty cool guy and he's working at a company that I might want to work at in the future (3-5 years from now). We talked for a little afterwards and I got his card. How am I supposed to keep in contact with him? Do I just send an email thanking him for taking the time to come talk to the class?