I need IP addresses for reputation

Number one of seven in our occasional series on why ESPs need, or don’t need, lots of IP addresses to send mail properly.

I need at least one IP address per customer, to handle IP based reputation

Why this is right
While DKIM is gradually moving the main key for reputation tracking to a domain based token, right now the main key that is used to track reputation is the sending IP address.
If you have multiple customers sending mail of different quality using a different sending IP address for each of those customers means that the good customers will not be penalized by the poor behaviour of the bad customers. And, just as importantly, poor customers will not benefit from the behaviour of the good customers. This allows receivers to track sender reputation more accurately, and so delivery just wanted email to their recipients better. That makes everyone happy (other than the bad customers who deserve to be unhappy until they fix their practices).
Why this is wrong
Reputation is tied to sending IP address, but it’s also affected by volume of emails received from that IP address, and the consistency of volume. If a customer is only sending a few hundred emails a week to any given receiver ISP or they’re only mailing monthly then they won’t be able to maintain much of a positive reputation, simply because they’re too small to keep track of or because they mail so infrequently that each time they mail the receiving ISP will have forgotten about their previous mailings. In those cases the sender will be treated much the same as a new sender from a given IP address (neutral, at best, maybe poorly). For those cases a customer is likely to get better delivery rates if their mail is sent through an IP address pool that sends enough email overall to be noticed and tracked by receiving ISPs.
Another reason this is wrong
Reputation is tied to sending IP address, but receiving ISPs aren’t stupid and do recognize attempts to game the system. If you’re an ESP with a mix of good and bad customers then segregating the IP addresses they send from will not completely isolate the reputation of those customers from each other. The bad customers will drag your reputation as an ESP down more than the good customers will pull it up. And as your reputation as an ESP degrades it will pull down the reputation of your good customers much more than it will increase the reputation of your bad or unknown customers.
So segregating senders onto their own IP addresses doesn’t entirely separate their reputation from each other or from their ESP. And if you believe it does, you’re likely to make business decisions based on that misunderstanding that will badly affect your reputation and the delivery rates of your customers. Don’t fall into that trap.

Godzilla sneaks up on Tokyo
Godzilla sneaks up on Tokyo

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Why do you need so many IP addresses (part 2)?

In my last post I discussed the background as to why an ISP will require their users to use their IP address allocation efficiently. I also mentioned in passing that I’d discussed ESP address allocation with both ESPs and ISPs recently.
The ESP was talking about assigning a couple of dozen IP addresses to each customer, because they might be useful for spreading load and it would provide some flexibility for moving from one IP address to another if one should get blocked. And IP addresses are pretty much free. They were wrong.
The ISP was considering an application for 750 IP addresses from a new ESP customer. They assumed that there was no possible reason other than snowshoe spam for an email related customer to need that many IP addresses. While I suspect they may have been right about the specific potential customer, the general assumption was wrong.
I’ve seen a lot of reasons given by ESPs for why they need so many IP addresses:

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Confirmed opt-in

I spent the morning in multiple venues correcting mis-understandings of confirmed opt-in. The misunderstandings weren’t so much that people didn’t understand how COI works, but more they didn’t understand all the implications.
In one venue, the conversation centered around how small a portion of deliverability the initial subscription process affects. Sure, sending unwanted, unexpected email can and does cause reputation problems, but merely using COI as a subscription methodolgy doesn’t automatically give a sender a good reputation or good delivery. Senders using COI as a subscription practice need to also need to send relevant and engaging mail that their recipients expect to receive. They need to handle their bounces well and purge or re-engage inactive subscribers. They need to keep their complaints low and their responses high.
How you manage subscriptions is only one factor in reputation schemes, and even if the subscription method is COI other factors can negate any bonus involved.
The second conversation involved Ken challenging me on the comment I left on his quiz yesterday. I said COI wasn’t foolproof and he challenged me to explain how. I did, and he’ll be following up next week.

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Rescuing reputation

One of the more challenging things I do is work with companies who have poor reputations that they’re trying to repair. These companies have been getting by with poor practices for a while, but finally the daily delivery falls below their pain threshold and they decide they need to fix things.
That’s when they call me in, usually asking me if I can go to the ISPs and tell the ISPs that they’re not spammers, they’re doing everything right and will the ISP please stop unfairly blocking them. Usually I will agree to talk to the ISPs, if fixing the underlying problems doesn’t improve their delivery on its own. But before we can talk to the ISPs, we have to try to fix things and at least have some visible changes in behavior to take to them. Once they have externally visible changes, then we can ask the ISPs for a little slack.
With these clients there isn’t just one thing they’ve done to create their bad reputation. Often nothing they’re doing is really evil, it’s just a combination of sorta-bad practices that makes their overall reputation really bad. The struggle is fixing the reputation requires more than one change and no single change is going to necessarily make an immediate improvement on their reputation.
This is a struggle for the customer, because they have to start thinking about email differently. Things have to be done differently from how they’ve always been done. This is a struggle for me because I can’t guarantee if they do this one thing that it will have improved delivery. I can’t guarantee that any one thing will fix their delivery, because ISPs measure and weight dozens of things as part of their delivery making decisions. But what I can guarantee is that if they make the small improvements I recommend then their overall reputation and delivery will improve.
What small improvement have you made today?

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