All filters are not equal

Many questions about delivery problems often assume that there is one standard email filter and the rules are the same across all of them. Unfortunately, this isn’t really the case.

The biggest divide is consumer versus business filters. Business filters don’t really care about things like engagement. A sender could have near perfect engagement with a message to a business. But a decision maker inside the company can still decide that mail doesn’t get in. There’s no appealing to permission or wanted mail. Employee mail is provided for the good of the business, not for the good of the individual user or the sender.

There are other less obvious divides between filters as well.

I frequently refer to “webmail providers” (Oath, Microsoft, Gmail). These are companies that control the mail delivery and, for the bulk of their customers, control the mail client as well. They can use engagement filters because they have more data. Other companies, like broadband providers or web hosting services, don’t have the same level of access to customer behaviour, so they can’t heavily use engagement as part of their filtering processes. They may have some access to IMAP folders, depending on their setup, so they can look at some engagement flags.

Filtering companies also have their own type of filters. In many cases, though, they have no access to any engagement filters. They handle mail at a discrete point that starts during SMTP sessions and ends when the mail is handed off to the local delivery agent. These companies cannot use engagement as part of their filtering process all, they simply don’t have access to that data.

Understanding what data filters act on and what data they have access to can inform how to deal with blocks and delivery problems.

 

DNS Flag Day
Fun with spam filters

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It depends… no more

The two most hated words in deliverability. Many people ask general questions about deliverability and most experts, including myself, answer, “It depends.”
There are a lot of problems with this answer. The biggest problem is that it’s led to the impression that there are no real answers about deliverability. That because we can’t answer hypothetical questions we are really just making the answers up.
Depositphotos_53649203_original
The reason we use “it depends” is because the minute details matter when it comes to deliverability. Wether or not something will hurt or help deliverability depends on the specific implementation. Who’s doing the sending? What is their authentication setup? What IP are they using? How were the addresses collected? What is their frequency? What MTA is used? Are they linking to outside sites? Are they linking to outside services? Where are images hosted? The relevant questions go on and on and on.
I am going to stop saying it depends when answering generic deliverability questions. Instead I will be using the phrase “details matter.” Details do matter. Details are everything. Details drive deliverability.
Details Matter
The importance of details is why many deliverability people hedge their answers. The details do matter.
I will do my best to stop answering It Depends to deliverability questions. Instead, I’ll be answering with question and pointing out the details matter.
 

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Use the form…

A lot of senders get frustrated with the time it can take to get a response from some ISPs. It’s totally understandable, for a lot of companies delivery problems are all hands on deck level problems. They want them fixed and they want them fixed IMMEDIATELY. They want feedback that their issue is being addressed. They want to know someone at the ISP knows there is a problem.
I’ve talked before about visiting my friend Anna and watching her laptop screen explode with IMs from senders who wanted help with an AOL issue. She’s awesome and conscientious and tried to address all of those issues as fast as she could. She did want senders to feel like their issues were important and that someone inside AOL cared about the mail blocks.
SpecialSnowflake
I was always a strong advocate for following the official pathways for addressing problems. That was the whole point of the 2009 blog post. These days it’s easier to do than it ever was. Many ISPs have forms and process around handling delivery issues. This is good! In the past getting an answer to “why is my mail blocked” required knowing the right people. Now, it’s not about who you know. The ISPs and filtering companies who are open to senders have postmaster pages, unblock forms and official request channels. Those that don’t have those channels have made certain business decisions to not provide support for senders.
Despite the availability of webforms and knowledge bases and detailed information, a lot of people still think that the only way to get attention or get an issue addressed is to get someone on the phone. It’s not, though.
ISPs have their processes. If you want things handled quickly use those processes. Even in the places where very helpful reps are, they can’t (on order of lawyers and executives) help people unless there is a ticket already open.
Always, always use the recommended processes before trying to find “a real person.” Most of the time your issue can be solved faster if you fill out the form than if you hunt around for a person. In the worst case, all that time will be wasted as the person in question will tell you to fill out the form.
 

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Filters do what we tell them

In the email space we talk about filters as if they were sentient beings. “The filters decided…” “The filters said…” This is convenient shorthand, but tends to mask that filters aren’t actually deciding or saying anything. Filters are software processes that follow rules dictated by the people who create and maintain them. The rules flow from the goals set by the mailbox provider. The mailbox provider sets goals based on what their users tell them. Users communicate what they want by how they interact with email.

What we end up with is a model where a set of people make decisions about what mail should be let in. They pass that decision on to the people who write the filters. The people who write the filters create software that evaluates email based on those goals using information collected from many places, including the endusers.
What mail should be let in is an interesting question, with answers that differ depending on the environment the filter is deployed in.
Consumer ISPs typically want to keep their users happy and safe. Their goals are to stop harmful mail like phishing, or mail containing viruses or malware. They also want to deliver mail that makes their users happy. As one ISP employee put it, “We want our users to be delighted with your mail.”
Businesses have a few other goals when it comes to filters. They, too, need filters to protect their network from malicious actors. As businesses are often directly targeted by bad actors, this is even more important. They also want to get business related email, whether that be from customers or vendors. They may want to ensure that certain records are kept and laws are followed.
Governments have another set of goals. Universities and schools have yet another set of goals. And, of course, there are folks who run their own systems for their own use.
Complicating the whole thing is that some groups have different tolerances for mistakes. For instance, many of our customers are folks dealing with being blocked by commercial filters. Therefore, we don’t run commercial filters. That does mean we see a lot of viruses and malware and rely on other strategies to stop a compromise, strategies that wouldn’t be as viable in a different environment.
Filters are built to meet specific user needs. What they do isn’t random, it’s not unknowable. They are designed to accomplished certain goals and generally they’re pretty good at what they do. Understanding the underlying goals of filters can help drive solutions to poor delivery.
Use the shorthand, talk about what filters are doing. But remember that there are people behind the filters. Those filters are constantly maintained in order to keep up with ever changing mail streams. They aren’t static and they aren’t forgotten. They are updated regularly. They are fluid, just like the mail they act on.

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