Yes it is very safe. I reccomend trying not to even get the clerk involved. My WalMart has a drop box that I put the film in myself. If you have to hand it to them, make sure you write send out and all the other good stuff like Kodachrome slides, process K-14 only. Kodak has discontinued their mailers. The only options left are WalMart, Rite Aid, Walgreens (?), and mailing it in yourself. I use to use Qualex, but since they are closing this Friday, I have switched over to mailing directly to Dwayne's. I personally don't care for WalMart's stores or employees too much. I do use them on occasion to save costs. I don't have my own scanner, so when I need a CD I always mail in directly and I get a CD back for $4.95 with scans that are good enough for the web and sometimes for 4X6 prints.