I'll add another way to find them, onto what Pat said. Pat's list is good. I don't see how Vince's idea would work unless you know the account number which is a seemingly random number. Granted Jessica said the person gave her some numbers, so maybe. My idea would be: Jessica start a New Campaign (this is Free and unlimited, so even if you're not going to be the GM of the "actual" campaign, you can still start a free campaign as a holding-tank and meeting-place to collect your friends). In the campaign, as GM, Jessica click Invite Players. Here you can enter the person's email address, and it will email the campaign link to them. Once the person accepts the email and joins the campaign, Jessica can easily find the person by entering your campaign.