What stops your email campaigns from getting delivered? What’s considered as spam? And how does an email spam filter work anyway? This article takes a deep-dive into the journey of email and the various spam filters it encounters along the way.
If you’re an email marketer, you’ll know how important email deliverability is to the success of your campaigns.
So, why is it important to know about email spam filters?
Understanding spam and how email spam filters work will give you a better chance at inbox placement. Because, let’s be honest, if your emails don’t make it to your contacts’ inbox, then you might as well not send any emails at all.
This knowledge will also come in handy when choosing an email marketing platform. While there are some deliverability best practices a marketer should use to get past spam filters, a lot of the deliverability heavy lifting is done by the ESP. So naturally, you’d want to choose a good one.
What is spam?
Before we can talk about spam filters, we have to understand spam itself.
First came email.
Many people think that spam is equivalent to a scam. Scams can be many things, from the Nigerian Prince Scam to phishing emails posing as banks needing croatia mobile phone numbers database you to re-confirm your personal details, to advertisements for male enhancement pharmaceuticals. And email is just one of many forms – and perhaps the most common – that scams can take.
But while many scammers do send bucket loads of spam, spam and scams are two separate things.
Scam emails are malicious spam. But you don’t have to have nefarious intent to be a spammer.
What characteristics classify an email as spam?
The U.S. Federal Trade Commission defines spam as “unwanted commercial email” (UCE). And the Spamhaus Project, the biggest international nonprofit how to improve local seo in a small town? organization fighting spam, defines it as “unsolicited bulk email” (UBE).
Although they differ slightly, what these definitions have in common is they stress that to be classified as spam, an email needs to meet two criteria:
It is unwanted or unsolicited. This means the recipient did not ask to get this email.
It is sent in bulk to many recipients (as opposed to just one or two).
Many people will tell you that “spam is in the eye of the beholder” and “one person’s spam is another person’s ham.” That is absolutely correct.
A recipient defines what spam is, not the sender.
Occasionally recipients sign up for legitimate email marketing, and then they forget they signed up for it.
In that case, it’s, unfortunately, still a type of spam. It is unwanted. That’s why you always need to provide all recipients the option of unsubscribing from your list in every single email that you send. If a contact decides that your email is spam, they have a quick and easy way to stop receiving email from you.
As an email marketer, you don’t get to say if you’re sending spam or not, your contacts decide. Your best bet is to send bulk emails without spamming.
Why were email spam filters created?
In the 1990s, the email industry was booming. The number of email users skyrocketed globally in the mid- to late-90s.
While everyone and their mothers were signing up for an email address, marketers began to go crazy over the potential of email marketing. But they weren’t all savvy enough to use consent-based marketing or double opt-in marketing.
Unsolicited emails flooded people’s inboxes, often causing them to overlook important messages and prevent all meaningful communication.
Naturally, people came up with ways to block these unwanted emails. And that is how anti-spam solutions were born.
With the advent of email filters came the idea of email deliverability, and the need for email service providers. Sending out messages in bulk usually signified to internet service providers (ISPs – like Gmail, Outlook, Yahoo, etc.) that you were a spammer.
So email marketing services like Brevo were born: as a means to send legitimate permission-based email marketing campaigns.
Now that we’re all on the same page about what conduit china spam is and where the term came from, we’ll look at how ISPs keep out spam today.
The journey of an email: The spam filters it encounters
Despite its instantaneous nature, every single email you send has to complete a long journey from the sender to the recipient.
It passes through multiple filters, which run authentication processes, as it travels through the internet from one server to the next.
In the case of email marketing, you are probably using an email service provider (ESP) like Brevo to send your email campaigns.
Typically, when an email gets past spam filters, its journey goes a bit like this:
Step 1: Pressing send
You hit send and the message leaves the outbox.
Step 2: Leaving the MTA (Message Transfer Agent)
The message passes through the MTA’s outbound filters.
Before the message transfer agent (MTA) releases your email from your server or the ESP’s onto the internet, it must be checked by internal filters. If an ESP does not have internal filters set up to monitor and catch spam, then your ESP is not doing its job.
These internal checks ensure that no spammers are trying to make use of your ESP’s software and servers. Every ESP should run their own checks, and what constitutes those checks is usually proprietary and top secret.
Step 3: Traveling the internet
As tiny bits of data, the email passes from router to router on the internet where it gets mixed in with all the other billions of email messages sent around the globe every day.
Step 4: Getting through the gateway filter
The message is checked by your ISP’s gateway filter and either enters the server or is rejected.
This is the first email spam filter your message may encounter – an initial set of checks. If your email fails to pass the guards at this gate, it will not make it onto the ISP’s server.
This filter works on an SMTP basis, which stands for simple mail transfer protocol, and functions like a firewall for your email server.
It might decide to not let your message in for any number of reasons – e.g., a faulty/outdated recipient address or an overly large attachment. But other reputation reasons can come into play here, as well, such as a poor IP reputation or a blacklisting. (One way to quickly check your IP reputation for free is to figure out its sender score.)
The gateway filter also examines technical elements of the email’s header and any authentication it uses, such as DKIM, SPF, and DMARC.