If you have an order stuck in payment pending due to an incorrect PayPal email address in your shop, one of the following options may be of assistance in successfully claiming the funds.
Since a PayPal account can have more than one email address attached, you can add the old email address (or incorrect email address) to your current PayPal account, verify it and see if the payments then come through.
If that does not work or you simply have no access to that email account, you may have to speak to PayPal for advice on how to claim the fund.
Notify your customer to cancel the PayPal payment and place the order afresh.
This option is not ideal but may be necessary if all else fails.