what i think happened is that RYAN was the one that sent KAREN the email.
He was lying to kelly.
There was an episode in season three that went into it, but i forget which one, sorry :S

it was women appreciation day for season 3 and ryan said he sent the e-mail to her...but this episode it said she sent him one.....

he was lying to kelly, like he probably lied to kevin and andy about meeting vince vaughn.

He sent one to Karen before he found out that she was with/serious about Jim. He lied to Kelly.

Ryan is a jerk, but its really funny. I like his character.

I think Ryan is lying...but what if...

Ryan showed up for his interview in New York, which was to take place right after Jim's. To rattle Jim before his interview, Ryan shows Jim an e-mail from Karen asking if he were still interested in going out. What if Karen sent this e-mail after one of her and Jim's many "talks" about his feelings for Pam (Benihana Christmas, Traveling Salesman, The Negotiation). Jim, then goes to look for Karen wherever she said she was going and breaks up with her because of the e-mail. Then he decides to ask Pam out because she would never play games like that.

Ryan was lying to Kelly about that. In reality Ryan had sent Karen an e-mail asking her out. But to make Kelly think that he had really cared about her he told her that it was Karen who had asked him out.