I would assume that they are busy and haven't got back to you or maybe they haven't logged into epals for awhile.I know I joined several years ago and used my university email account to let me know if I got a message, but I wasn't getting the emails that I received new emails(a fault of the university email forwards). Perhaps that may be the case. Or they should list themselves as inactive so they won't get any more correspondences about partnerships. Write another email after one week passes since your first and ask if they received your first mail. If they don't respond, move along.