Starting April 7, we will be adding the following list of IP addresses for www.paypal.com to the DNS:
This change should be transparent to most merchants and may not require any action on your part.
However, if you are using IPN for Order Management and your IPN listener is behind a firewall, you may need to update your firewall configuration to allow outbound access to these IP addresses. This action will ensure that your IPN listener does not get intermittent timeouts when performing IPN validation by posting back to https://www.paypal.com.
For more information on IPN, please refer to https://www.paypal.com/ipn
HOST 99 NOTE: We have already updated all servers to allow the new ip addresses effective April 7, 2011