It can feel really upsetting to get something by e-mail which you didn't want and lots of times it can be through no fault of your own. Similarly it can be really creepy if you trusted someone you were chatting with, and then suddenly feel that they are lying or not who them seem.
We all makes mistakes. Talk to a friend, teacher or parent if someone, or something you see or receive on line makes you feel uncomfortable. Make sure you look out for your friends and family and realize that we - adults and young people alike - all need to learn to take control when using the internet.