If I find an advertisment on a site such as craiglist and use the ad on my site to connect one of my users with the original advertisment poster can that cause any legal problem?
I am reposting the ad in my site, the user submits it and then it is submitted to the original poster (The ad may contain identifying information such as a company name).
First of all, IANAL, so you may want to talk to a real attorney in this regard. But I am pretty sure that as long as you are just linking to the ad (with a no liability note in the footer) you should be good. However from your post it looks like you are copying the full ad to your website, and the user submits a reply on your webpage, which you forward to the original poster. Well, that is a copyright violation. When someone posts an ad on CL, they are granting all the rights to CL (read CL's terms of use).