Replying to HELP how to send high res images via email

Hey guys, i'm looking to take some pics from NS photo gallary and blow them up to a larger size to hang in my ski shop as posters. The only problem is when i save the photo and send it as an attachment the resolution is not correct. I picked out 4 photos and sent them to the guy who was going to blow them up and print them but he said they are too low resolution and they would look bad. He said i need images at 30 dpi and the ones i chose were only 9. Any suggestions on how I can send them in a higher resolution or where I can find other action photos of skiing i would greatly appreciate it. Thanks