What does good IP Reputation get you?

laura
Industry
March 8, 2018

Today I was discussing some mailing list posts with an ESP colleague. He was telling me some interesting numbers he’d collected from different IP pools they maintain. He was testing routing mail through IPs based on subscription process and routing based on engagement metrics. The data showed that inboxing rates were similar across the test groups. As he put it, “IP reputation didn’t have much impact on inbox delivery.”

I’m not surprised. I’ve been talking for a while about how IP reputation is less important in reaching the inbox. In fact, it was almost 5 years ago now that I wrote The Death of IP Based Reputation. I updated it in 2015 with Deliverability and IP Reputation. Overall, IP reputation is a much smaller piece of reaching the inbox now than it has been in the past. I’ve talked about the reasons for this in the above posts. The short version is:

IP reputation is a crude hammer;
IPv4 addresses are in very limited supply, in network terms more customers / IP is a good thing;
Spammers use botnets, sending large amounts of email across many IPs;
IPv6 is huge and IP based blocking will be challenging and of limited effectiveness; and
Better computing power makes content scanning more feasible.

IP Reputation Still Matters, a little

This doesn’t mean senders can, or should ignore IP reputation. Even Gmail looks at IP reputation a little bit. The place IP reputation is primarily used during the SMTP transaction. Good IP reputation does lead to less rate limiting. Senders with good IP reputation can send more mail faster than senders with poor reputation. But once the SMTP transaction is over, IP reputation is just a small factor in a large pool of variables.

IP Reputation Still Matters, a little more.

There are some places that heavily rely on IP filters. And some places that rely on certain types of IP filters. Most of the major providers will block mail from home users, dynamic IPs, and infected machines. Additionally, there is and will probably always be a long tail of domains that are still relying on IP based filters. It’s a crude hammer, but it’s an effective one. Typically, though, IP reputation in those cases is in the eye of the root user. The good news is, these are often private networks, and users have the option to use less restrictive free providers if they’re not getting the email they want.

IP reputation and email delivery

IP reputation is a measure of how much wanted mail a particular IP address sends. This wanted mail is measured as a portion of the total email sent from that IP. Initially IP reputation was really the be all and end all of reputation, there was no real good way to authenticate a domain or a from address. Many ISPs built complex IP reputation models to evaluate mail based on the IP that sent the mail.
These IP reputation models were the best we had, but there were a lot of ways for spammers to game the system. Some spammers would create lots of accounts at ISPs and use them to open and interact with mail. Other spammers would trickle their mail out over hundreds or thousands of IPs in the hopes of diluting the badness enough to get to the inbox. Through it all they kept trying to get mail out through reputable ESPs, either by posing as legitimate customers or compromising servers.
These things worked for a while, but the ISPs started looking harder at the recipient pool in order to figure out if the interactions were real or not. They started looking at the total amount of identical mail coming from multiple IP addresses. The ISPs couldn’t rely on IP reputation so they started to dig down and get into content based filtering.
As the ISPs got better at identifying content and filtering on factors other than source IP, the importance of the IP address on inbox delivery changed. No longer was it good enough to have a high reputation IP sending mail.
These days your IP reputation dictates how fast you can send mail to a particular ISP. But a high reputation IP isn’t sufficient to get all the mail in the inbox. It’s really content that drives the inbox / bulk folder decisions these days.

Generally IPs that the ISP has not seen email traffic from before start out with a slight negative reputation. This is because most new IPs are actually infected machines. The negative reputation translates to rate limiting. The rate limiting minimizes people getting spam while the ISP works out if this is a real sender or a spammer.
Some ISPs put mail in the inbox and bulk foldering during the whitelisting process. In this case what they’re doing is seeing if your recipients care enough about your mail to look for it in the bulk folder. If they do, and they mark the mail as “not spam” then this feeds back to the sender reputation and the IP reputation.
If you’re seeing a lot of bulk foldering of mail, it’s unlikely there’s anything IP reputation based to do. Instead of worrying about IP reputation, focus instead on the content of the mail and see what you may need to do to improve the reputation of the domains and URLs (or landing pages) in the emails.

Spam is not a moral judgement

Mention an email is spam to some senders and watch them dance around trying to explain all the ways they aren’t spammers. At some point, calling an email spam seems to have gone from a statement of fact into some sort of moral judgement on the sender. But calling an email spam is not a moral judgement. It’s just a statement of what a particular recipient thinks of an email.
There are lots of reasons mail can be blocked and not all those reasons are spam related. Sometimes it’s a policy based rejection. Mailbox providers publishing a DMARC record with a reject policy caused a lot of mail to bounce, but none of that was because that user (or that mailing list) was sending spam. Most cable companies prohibit customers from running mail servers on their cable connection and mail from those companies is widely rejected, but that doesn’t mean the mail is spam.
Sometimes a block is because some of the mail is being sent to people who didn’t ask for it or are complaining about it. This doesn’t make the sender a bad person. It doesn’t make the sending company bad. It just means that there is some issue with a part of the marketing program that need to be addressed.
The biggest problem I see is some senders get so invested in convincing receivers, delivery experts and filtering companies that they’re not spammers, that they miss actually fixing the problem. They are so worried that someone might think they’re spammers, they don’t actually listen to what’s being said by the blocking organization, or by their ISP or by their ESP.
Calling email spam isn’t a moral judgement. But, if too many people call a particular email spam, it’s going to be challenging to get that mail to the inbox. Instead of arguing with those people, and the filters that listen to them, a better use of time and energy is fixing the reasons people aren’t liking your email.

You can't always get what you want

It’s a problem anyone who has done any delivery work has faced. There’s a client who is having blocklist problems or ISP delivery problems and they won’t pay any attention to what you say. They insist that you talk to the blocklist or the ISP or hand over contacts directly so they can “dialog with” someone internally. They don’t like what they’re hearing, and they hope that the answer will be different if they find a new person to talk to.
The reality is many of the people at ISPs and blocklists don’t want to talk to these types of senders. They may answer a friendly question from someone they know and trust, but sometimes not even then.
Some very large ISPs and major blocklists don’t even take sender questions. They won’t communicate with anyone about any delivery issues.
I’ve had to tell more than a few clients recently that various ISPs and blocklists weren’t interested in helping those clients with their delivery problems. There are two classes of reactions I get from clients. Some clients focus on moving forward. “OK, now what? How can we identify the issue, what data do we have and how can we figure out what the problem is?”
Other clients continue to look for ways to talk to whomever is blocking their mail. They’re convinced if they can just “explain their business model” or be told what they’re doing wrong, that all their delivery problems will magically disappear.
Needless to say those clients who focus on moving forward and looking at the information they do have have much better success resolving their delivery problems. What many senders don’t understand is the wealth of data they have that will help them resolve the issue. And even if they know it’s buried in their files, they don’t always know where to start looking or even what they’re looking for.
But that is, of course, why you hire someone like me who understands spamfiltering and email. I help senders understand how email filters work and identify what parts of their programs are likely to be responsible for delivery issues. I often find the most valuable service I provide to clients is a fresh set of eyes that can see the forest. With my help, they manage to stop obsessing unproductively about one particular symptom and focus on the underlying problems.
Senders who think the holy grail of problem resolution is speaking to the right person at an ISP or blocklist generally are disappointed, even when they hire someone who knows all the right people at the ISPs. They can’t always get what they want. But I can often help them get what they need.