Reputation monitoring sites

There are a number of sites online that provide public information about reputation of an IP address or domain name.

  1. Sender Score – http://senderscore.org/. Provided by Return Path. They collect data from some ISPs and blocklists. Using a proprietary formula, they calculate a sender score running from 1 – 100 for each IP address sending mail to their network. Higher scores means a better reputation. Can be inaccurate for IPs sending very low volumes of email. Some ISPs use Sender Score to feed into their delivery decision engines.
  2. Sender Base – http://senderbase.org/. Provided by Ironport / Cisco. They collect publicly available data as well as data from their userbase. Reputation is reported as “good” “poor” or “neutral.” Senderbase scores feed into some ISP delivery decision engines.
  3. AOL reputation – http://postmaster.aol.com/cgi-bin/plugh/check_ip.pl. Reports the reputation of IPs as determined by AOL. Uses a scale of “good” “poor” or “neutral”.
  4. RoadRunner blocks – http://security.rr.com/amIBlockedByRR. Reports if a particular IP address is currently being blocked from sending mail to Road Runner.
  5. Spamhaus blocks – http://www.spamhaus.org/. Reports if an IP is currently listed on any of the Spamhaus lists.
  6. Sendmail Reputation – http://sendmail.com/sm/resources/tools/ip_reputation/. Reports reputation of an IP address as measured by Sendmail.
  7. Trusted Source – http://www.trustedsource.org/. Provided by McAfee.
  8. Commtouch – http://www.commtouch.com/check-ip-reputation/. Provided by Commtouch.
  9. Barracuda Central – http://www.barracudacentral.org/lookups/. Provided by Barracuda, shows what IP addresses or domain names are currently blocked.
  10. SNDS – http://postmaster.live.com/snds/. Provided by Microsoft / Hotmail / Live.com. Will show IP addresses that are currently blocked by Microsoft.
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Public reputation data

IP based reputation is a measure of the quality of the mail coming from a particular IP address. Because of how reputation data is collected and evaluated it is difficult for third parties to provide a reputation score for a particular IP address. The data has to be collected in real time, or as close to real time as possible. Reputation is also very specific to the source of the data. I have seen cases where a client has a high reputation at one ISP and a low reputation at another.
All this means is that there are a limited number of public sources of reputation data. Some ISPs provide ways that senders can check reputation at that ISP. But if a sender wants to check a broader reputation across multiple ISPs where can they go?
There are multiple public sources of data that I use to check reputation of client IP addresses.
Blocklists provide negative reputation data for IP addresses and domain names. There are a wide range of blocklists with differing listing criteria and different levels of trust in the industry. Generally the more widely used a list the more accurate and relevant it is. Generally I check the Spamhaus lists and URIBL/SURBL when investigating a client. I find these lists are good sources for discovering real issues or problems.
For an overall view into the reputation of an IP address, both positive and negative, I check with senderbase.org provided by Ironport and senderscore.org provided by ReturnPath.
All reputation sources have limitations. The primary limitation is they are only as good as their source data, and their source data is kept confidential. Another major limitation is reputation sources are only as good as the reputation of the maintainer. If the maintainer doesn’t behave with integrity then there is no reason for me to trust their data.
I use a number of criteria to evaluate reputation providers.

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Link roundup June 18, 2010

Hotmail has released a new version of their software with some changes. Return Path discusses the changes in depth, but there are a couple that senders may find helpful.

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SPF records: not really all that important

I’ve been working through some Hotmail issues with a client over the last few months. One of the things that has become clear to me is how little Hotmail actually does with SPF records. In fact, Hotmail completely ignored my client’s SPF record and continued to deliver email into the inbox.
This isn’t just a sender that had a “well, we think most of our email will come from these IPs but aren’t telling you to throw away email that doesn’t” record. In fact, this client specifically said “if email doesn’t come from this /28 range of email addresses, then it is unauthorized and should be thrown away.” The email was being sent from an IP outside of the range listed in the SPF record.
As part of the process involved in fixing the delivery problems, I had the client update their SPF record and then I enrolled their domain in the SenderID program at Hotmail. This didn’t have any effect, though. Hotmail is still not checking SPF for this client. When I asked Hotmail what was going on they said, “We do not do lookups on every sender’s mail.”
So, there you have it folks. The last bastion of SPF/SenderID has abandoned the technology. Even a totally invalid SPF record doesn’t matter, mail can still reach the inbox at Hotmail.

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