Many Road Runner customers will find their IP address listed on one or more "blocklists"; in most cases, there is no cause for concern.
All Road Runner Residential customers, and many Business Class customers, have what are called "dynamic" IP addresses. Time was when people accessed the Internet from home using dial-up modems, it was common for a person to be assigned a different IP address each time he dialed in to his ISP; such IPs were called "dynamic IP addresses" because they would be re-cycled quickly and used by many different customers in a short period of time. Today, with more people using high-speed connections at their homes and their connection being on all the time, it's possible for a customer to use the same IP address for many months or longer; nowadays, the term dynamic means "subject to change, and solely at the ISP's discretion, not the customer's".
Even though a dynamic IP address may have a persistence to its assignment, there are still many sites out there (including Road Runner) that do not wish to accept any inbound mail directly from a dynamic IP address. To help them enforce this policy there are several blocklists in public use (including the Spamhaus PBL, the Trend Micro/MAPS DUL, and the SORBS DUHL, to name just three) that will list IP addresses solely as an assertion that the IP address is dynamic. Sites can then use these lists to enforce their inbound policy of no mail directly from dynamic IP addresses.
It's not uncommon for a customer to happen upon such a listing and immediately become quite concerned; if this sounds like you, there are some things you should know.
First, if you're using Road Runner's Mail servers to send email, your IP's listing as dynamic by any list should not affect your ability to send mail to anyone. Dynamic IP addresses are supposed to send mail using their ISP's mail servers, and so by using our servers, you're engaging in the kind of behavior that these lists seek to enforce. In most cases, if your IP's listing as dynamic affects your ability to send mail, it's likely due to an overzealous misconfiguration on the part of the receiving site.
Next, Road Runner's outbound mail servers do not use these blocklists to control access to our outbound servers; again, dynamic IP addresses are supposed to use their ISP's mail servers to send mail, and so we permit our dynamic IP addresses to access our outbound mail servers.
Last, if you think your mail is being rejected somewhere due to your IP being listed by a blocklist, please submit a full copy of the error message when you contact Customer Care, to allow us to properly diagnose the problem. If your IP is correctly listed as dynamic, we won't take any action to change the listing, but we will work with the site rejecting your mail to understand why they're doing so.