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Understanding Email

How to improve the deliverability of your email campaigns

3/17/2023 | Steve Shannon, Bits & Bytes

Welcome to a new edition of Bits & Bytes, where we explore the realm of technology as it applies to both the promotional products industry and the world at large. This month, let’s take a look at a topic that’s near and dear to my heart: email. More specifically, let’s learn a little bit about how email functions on a fundamental level. Then, armed with that knowledge, let’s look at some things you can do to improve the deliverability of your email marketing campaigns.

The Basics

It’s easy to understand how email works if you think of an email message as a physical letter you send in the actual mail. When you press “Send”, that’s just like putting your letter in the mailbox. Once the letter is picked up by a postal carrier, it then takes a multi-point journey through various post offices and sorting stations before arriving at its final destination. An email message works the same way, except that every stop on its journey (including being picked up by the mail carrier) happens at a special type of computer called an SMTP server. SMTP stands for Simple Mail Transfer Protocol; just as this name implies, an SMTP server's job is simply to transfer or relay your email message to another server, which in turn passes it to the next server, and so on until your email eventually ends up at the mail server that houses your intended recipient’s inbox.

And how, you may ask, do those SMTP servers know where to relay the message so it reaches your recipient? Well, just as the post office looks at the front of your letter to see who it’s addressed to and where they live, an SMTP server looks at the email address that your message is being sent to and performs a special query on the portion of the address called the domain. If we look at an example email address:


Everything to the right of the “@” (in this case example.com) is the domain. Domains are like houses on the internet. Some are bigger than others (e.g. google.com, amazon.com, promocorner.com), but they all essentially serve the same purpose – they help compartmentalize the internet and organize it so that it can actually function. As part of that process, domains all have a set of publicly accessible records that list any mail servers that are authorized to accept mail on that domain’s behalf, just like a house has a physical address where letters can be delivered. Thus when an SMTP server receives an email message and is trying to determine where it should be relayed to next, it queries the recipient’s domain to find the location of the mail server and then, assuming it can’t deliver to the mail server itself, relays to the next nearest SMTP server which then repeats the process.

Depending on where you live relative to your intended recipient, your email may pass through many different SMTP servers in various locations before your recipient actually gets it. Each time this happens – that is, at each “hop” in the chain – the SMTP server that relays your message adds its own “stamp” to it with the location and time it was processed. By examining these stamps, your recipient can see the path the email traveled and how long it took to reach them. This information is often key to determining where delays in email delivery occurred, as you can see exactly which SMTP server held onto the email longer than expected.

And that’s essentially it! The process isn’t any more complicated than how the postal service handles actual mail delivery; it just happens invisibly and (it should go without saying) a lot faster. Yet for all its simplicity and efficiency, email isn’t perfect … 

Actually, that’s a bit of an understatement. It would be more correct to say that email has a massive, glaring flaw that has given rise to arguably one of the most odious conjurations of the modern era – spoofing.

The Flaw

At its inception, email (before it was even called “email”) was intended for simple internal communications within the ARPANET (the precursor to the modern internet). While it eventually evolved and was introduced into other networks as the young internet took shape, those early iterations were never designed to act as a worldwide ubiquitous communication medium. As such, an inherent flaw was baked into its basic functionality that, I’d like to think, its innovators probably would have addressed had they had the foresight. That flaw is that it was possible for anyone to email anyone – as anyone.

The act of spoofing – forging an email to make it appear that it was sent from someone else’s address – is so embarrassingly easy that literally anyone with a little know-how can do it. It’s so ingrained in the way that email works that, rather than correcting the problem at the source, the greater technological community has spent decades coming up with various defensive strategies to contain the fallout instead.  And it has allowed spammers, many of whom still remain unidentified, to send trillions of emails and rake in millions of dollars every year while avoiding prosecution.

Obviously, that last one poses a problem for anyone in the email marketing business. Spoofed emails and spam have become so prevalent that the rules put in place to stem their tide quite often interfere with legitimate marketing campaigns. It’s unfortunate, but this is the pond we swim in. Knowing that though, what can we do to help differentiate our emails from spam, increasing the deliverability and reach of our campaigns in the process?

The Application

Sending out email marketing campaigns can feel a bit like shouting into the void if you’re not getting the engagement you want. You might feel the urge to start sending flashier and more detailed campaigns more frequently to catch people’s attention, or you may be tempted to use a purchased list of potential customers’ email addresses to speed things up. While the impulse is understandable, I highly discourage anyone from taking either of these approaches, as the resulting damage they can do to your sending reputation could prove to be insurmountable. In particular, purchased lists often contain “honeypots” –  dummy email addresses set up specifically to catch spammers – and including one of these trap emails in your list can wreak utter havoc on your deliverability. 

And that’s the crux of it, really – the deliverability of your campaign is ultimately determined by your sending reputation, and so improving deliverability means differentiating yourself from run-of-the-mill spam. That entails maximizing the legitimacy and value of your campaigns for your existing list members and then growing your list gradually over time. While there’s no shortcut to a sterling reputation, there are some things you can do to help get you there faster:

  1. It may sound obvious, but one of the best ways to improve the reputation of your email campaigns is to make sure you’re broadcasting content that people actually want it; this refers as much to the information being presented in your email as the look and feel of it. For instance, if your email contains an overabundance of text, is overly long or has no clear theme, it can come across as disorganized which makes it easy for your recipients to miss the things that might interest them. Additionally, things like spelling errors, grammatical mistakes, low resolution images or broken links leave a bad impression and serve to diminish the legitimacy and professionalism of your campaign.

  1. When designing your campaign, try to avoid the scattershot approach of including something for everyone, especially if it would mean adding unnecessary bloat to your email. Put another way, if you find that you have a lot of information contained in a single campaign, think about splitting it into smaller campaigns that are more focused on the content you’re most wanting to highlight. This can make them feel more purposeful and relevant to your recipients. Keep in mind that the more recipients that open, click on, and engage with your emails, the more ISPs will view your email campaigns as providing valuable content which will help lower your spam rating and build your reputation faster.

  1. ISPs like it when they see you’re actively maintaining your sending list and keeping it up-to-date. This means including an active return address on your campaigns so that you’re able to receive any potential bouncebacks; it also means monitoring those bounces for dead or undeliverable email addresses and removing those addresses from your list as soon as possible. Continuously bouncing campaign emails off the same undeliverable address over and over is a great way to tank your reputation with an ISP. Additionally, if someone requests to be taken off your list, make sure to respond to their unsubscribe request in a timely manner. Having a bunch of people report your next campaign email as spam because you didn’t process their unsubscribe requests the first time can be detrimental to your reputation.

I’m reiterating here because it’s important – don’t use a purchased list for your campaign, no matter how much you’re tempted. The risk of ending up on a blacklist or being dropped by your mail service for emailing a honeypot far outweighs any perceived benefit of artificially growing your email list. If you instead focus your efforts on generating campaigns that look sharp and provide value for your recipients, your list will grow naturally as your reputation does.

Steve Shannon has spent his entire professional career working in tech. He is the IT Director and Lead Developer at PromoCorner, where he joined in 2018. He is, at various times, a programmer, a game designer, a digital artist, and a musician. His monthly blog "Bits & Bytes" explores the ever-evolving realm of technology as it applies to both the promotional products industry and the world at large. You can contact him with questions at steve@getmooresolutions.com.
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