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Email Deliverability 101: The Backbone Of Email Marketing

By Beth HendersonComments

Email Deliverability 101: The Backbone Of Email Marketing

The way we consume content, the way we behave from day to day, the way we shop - it’s all changed. And this transformation ain’t slowing down anytime soon.

As marketers, it’s up to us to catch up, keep up, and surpass the rowdy rabble of a crowd around us. We need to adapt and move with the times to avoid getting swallowed up, spat out and left in a puddle of shame…

That doesn’t necessarily mean you have to go out and find the sexiest strategy or the loudest communication channel of the moment. Sometimes, old is gold. It might just need a little bit of a polish.

This is why I took some time to get my head down in HubSpot’s email marketing certification. After a few hours watching webinars and a 90 minute exam, I went and passed with 92%.

Once a girly swot, always a girly swot.

But this isn’t a blog post about how best to show off about your glossy new badge (a perk nonetheless.)

You have to take what you learn and apply it…

The certification covers a lot, from email strategy and functionality to lead nurturing and optimisation. So, for someone getting increasingly more involved in how we use email marketing for our clients, there was plenty for me to reflect on.

Let’s face it, email marketing has been around for a long time, and it’s going to be around for a lot longer. Particularly in inbound marketing…

The dream team

Your customers have the power. Inbound marketing embraces this reality. It empowers people and provides them with helpful content that delivers real value.

But it doesn’t go about rudely interrupting them to achieve this.

Inbound draws people in, making email the perfect wingman.

Forget old-school email marketing strategies (if you can even call it a strategy). Buying cheap email lists and pushing your message in front of as many people as possible - whether they want to see it or not - is a dirty, impersonal tactic that won’t get you far.

*Whilst poor quality lists in the darkest corner of the internet should be avoided, this doesn’t rule out data from reputable partners. As long as their database has given permission to receive marketing information from affiliated third parties and their database is clean.  


You need to market to people the way they want to be marketed to.

Remember that you’re communicating with another human - your emails need to reflect this if you want to see real returns.

So, armed with my new certification, I’m here to shed a little light on how you can take your email performance to new heights.

From zero to hero

Think of a great marketing email you’ve received recently - one you’ve engaged with. Now think about why it grabbed your attention…

Was the content engaging?

Did the design support the message?

Was it relevant to you?

Did it help you with a particular challenge or goal?

Were the CTAs compelling?

All of these elements are important…

Together they make something great; miss just one and, well, it’s like #bingate all over again. A catastrophe. (Or cake-tastrophe in Iain’s case... GBBO fans here only please!)

giphy (1).gif

Best practice dictates that your emails should be delivered to a segmented list from your contact database, and they should include personalisation - even at the most basic level. They should also be designed and written to compel people to take the desired action.

Granted, it’s possible that the great email I asked you to think about didn’t quite tick all of these boxes. But something all of your favourite emails have in common: they made it into your inbox and were given the chance to shine.

Deliverability is the backbone of effective email marketing.

Without it, you’ve put time and effort into writing, designing, segmenting and testing something no one is going to see.

To ensure your content has the best chance of making it into your contact’s inbox, here are the ABCs of email deliverability…

The what, why, and how

There isn’t a magic formula proven to outsmart the spam filters. You have to understand what boxes your email needs to tick to make it into the inbox. It’s about interpreting what happens after you click send; what do the numbers say about your content?


“Email deliverability is the measurement and understanding of how successful a sender is at getting their marketing into people’s inboxes.” - HubSpot

And there are many more benefits to deliverability than you might think:

  • Nurture customers. Email is perfect for your customers, whatever stage of the buying journey they are at. Using segmentation and personalisation, you can nurture them through the funnel to taking a specific action. But if you can’t even make it into the inbox, then what chance do you have of encouraging opens, clicks, and conversions?
  • Boost future emails. Ignoring deliverability, even once, will drag your email performance right down. Every email effects the next, and problems can spread. By nailing this from day one, you’re putting yourself in a much better position for all future efforts.
  • Measure your metrics. As soon as open rates decrease and click throughs slow, marketers tend to jump to (the wrong) conclusions. It’s possible that your experiment with a new, edgy subject line influenced opens. It’s also possible that the size of your CTA deterred clicks. But the most likely cause is in your deliverability.

So that’s the ‘what’ and the ‘why’ covered, what about the ‘how’?

There are three things you need to determine before you can start sending inbound emails to contacts (and boost your chances of making it into their inboxes):

  1. Where have your contacts come from?
  2. What permissions have they granted you?
  3. What content and communication are they expecting from you?

HP only…

...make sure your contacts are from the best source.

Sauce? Source? No? OK, moving swiftly on…

Have they been engaging with your content? Did they convert on one of your forms? FABULOUS, these are contacts you need to be communicating with.

Please Sir, can I have some more?

This one is super important.

Everyone you intend to email must have given you the go ahead to do so.

Make sure the words you use on landing pages, subscription forms, and any other way you’re capturing leads, is clear. Contacts should be able to say ‘yes, I want to receive marketing information for you.’ If they can’t, then have you really got their consent?

Another easy way to get this consent is through your form criteria!

If you’ve just bought a list of poor quality data, stop. There’s really little point in spending time creating an email strategy. Sending content to people who haven’t given you permission will simply discredit your brand and deliver nothing of real value.

If you’re struggling to grow your contact list organically, then consider working with a relevant and reputable partner or publisher. As long as their (clean) contact database has agreed to be contacted by you, you’re good to go. Just make sure you ask the right questions to qualify the list’s quality:

  • How many people are on the list?
  • How were they collected?
  • How engaged are they?
  • Have they given permission to be contacted by a third party?

Sorry, who is this?

Getting permission is one thing, delivering content in line with these permissions is another.

Before you send anything, determine whether they’ll be expecting it or not.

Do they know who you are?

Do they know why they are getting this email?

Do they know when they granted you permission?

If you answered no to any of these, then I suggest you change your content to remind them. Don’t get me wrong, you don’t need to send them their entire customer journey with your brand - just a polite reminder of your relationship.

Top tip: use source information to segment your contacts and personalise this reminder based on their previous interactions with you.

And there you have it; three essentials of successful email deliverability. Trusting you’ve written and designed something of actual value to the contact, that is! Otherwise, there’s still a chance you’ll rub anti-spam services up the wrong way.

Here are some of the most common spam triggers you need to avoid:

  • There’s nothing positive about subject lines that shove offers, deals or competitions down your contacts’ throats. Think ‘buy’, ‘opportunity’, ‘quote’ or ‘subscribe’. HubSpot have put together a handy list of spam words to avoid in your email subject lines.
  • Don’t be a stranger! At the very least, make sure you use the contact’s first name. The best emails will draw upon their key challenges or goals, their job role or their industry. If you don’t even have their first name then ask yourself how clean your database actually is.
  • Rushed content leads to spelling errors and grammatical slip ups. We’re all human and we’re all bound to make a mistake from time to time. But spelling mistakes make your brand look sloppy - ask your team to check and double check your work...
  • … And don’t forget your links. Broken links or links to crappy destinations are going to upset anti-spam servers.
  • There’s a fine line between brilliant and garish design. Keep your formatting as straightforward as possible - let’s be honest, no one has enjoyed reading emails with seven different font sizes and various font colours since they were 13.    

The metrics that matter

You’ve got your email strategy, you’ve written the content, you’ve designed it, you’ve segmented your lists and you’ve set yourself up for excellent deliverability scores.

And then you click send…

It’s gone. It’s out there for the world to see. Now it’s time to review and analyse the results.

To ensure you’re always improving your email programme and delivering the right content, to the right people, at the right time, it’s fundamental that you spend time reviewing your email metrics:

  • Opens
  • Clicks
  • Bounces
  • Unsubscribes
  • Spam

Email Marketing Metrics.png

Don’t get bogged down in all the detail for now, focus on identifying trends from your last few email sends. Comparing these metrics across multiple emails will reveal a lot about your deliverability…


There’s a lot of debate about whether you can actually rely on ‘opens’. For example, if a contact has blocked images or the images don’t load properly, the tracking pixel won’t get loaded - skewing open numbers.

This is why looking at the general trend is key.

If you start noticing opens are dropping, even when your contact list is growing, then you need to take a step back and ask ‘am I sending this to the right people?’. If you have contacts in your list who have a history of ignoring and not opening your emails, stop badgering them.

They’re clearly not interested in what you’re saying at the moment. Don’t push them into unsubscribing - or worse, marking you as spam. And avoid give anti-spam servers an excuse to mark you as a bad sender.  


Clicks don’t lie. And they’re a great sign that you’re doing something right.

If clicks start to drop, but opens are unaffected, there might be a problem with your CTAs. Make sure you’re not shoving a load of different links and buttons to different offers and destinations in one email send.

Each email should have one primary goal. It should be encouraging contacts to take a desired action - visiting your website, for example. Make it clear what you want the contact to do and why they should do it. And make it easy for them to do it!

Using visual and text CTAs to send people to your website via your email is probably going to get some clicks. But if you’re providing three different CTAs to three different destinations, it’s going to get a little crowded.

People just don’t have time to waste on deciphering an email to understand what and where they should be clicking... 

Keep it simple!  



There are two key types of bounces that you need to be aware of:

  • Soft bounce: If an email has soft bounced, you can try getting in touch again later. This is something your Email Service Provider (ESP) will manage automatically. Soft bounces include temporary bounces, and sometimes reputation bounces.
  • Hard bounce: On the other hand, hard bounces can’t and shouldn’t be emailed again. Hard bounces include recipient bounces, content bounces, reputation bounces.

Recipient bounces are probably the most common type of hard bounce and occur when the recipient’s email address is wrong. To ensure your email list is as clean and up to date as possible, make sure you remove any incorrect emails from your database. And if you know someone is moving company, ask them to update their contact details!

An increased number of temporary bounces (soft) usually suggests that your email has content issues and the server can’t decipher whether your email should be delivered.

They’ll either try again, or they won’t.

A rise in temporary bounces is usually followed by a spike in content and reputation bounces (hard).

If a server or anti-spam service takes a dislike to your content, they’re not going to send it through. This is a content bounce. Typically this will be because you linked to something they didn’t like, your content is weak or littered with errors, the template is poorly designed, or it isn’t relevant to the recipient.

Reputation bounces highlight why every email you send is important. Based on your reputation and how well your emails have performed in the past, the server will make a judgement call on whether the recipient should receive content from you.


It’s not nice to feel rejected, I get that.

But while unsubscribes aren’t ideal, they’re not as bad as being marked as spam.

Take unsubscribes as a reason to switch up your strategy. If contacts are saying your content didn’t meet their needs or it had little value to them, then think about why…

Refer back to their source and their previous interactions with your brand. Was this email really tailored to them?

There are two key things we can infer from a spike in unsubscribers:

  1. You’re actually making it into their inbox, yipee!
  2. You’re not quite meeting their expectations.

Warning: If there’s a significant dip in unsubscribes combined with a drop in engagement, you’re probably not making it into any inboxes anymore.


If anything’s going to put a damper on your reputation of consistently delivering relevant and valuable content, it’s going to be contacts marking you as spam.

There’s no hiding from it. It suggests that you’ve really p’ed someone off, and email servers don’t want to risk connecting a brand that’s riling people up with their contacts.

Whilst a few spam complaints is normal (don’t go panicking if you’ve received one or two in the last 5 email sends), every ESP has a limit. Once you reach that limit, that’s it. You're done. Finito.  

Before sending every email, refer back to source, permission and expectation. Creating and delivering content in line with this will ensure you’re sending the right stuff to the right people.

Righting your wrongs

If you’ve sent a couple of emails and experienced a drop in engagement or rise in bounces / unsubscribes / spam complaints, it’s time to take a step back and right your wrongs.

Start with the three things that impact deliverability most significantly:

  1. Sources
  2. Permissions
  3. Expectations

Has your contact list come from a quality source? Have they engaged with your brand and opted in to receive content from you? Have you sent them something that they would expect to receive from you?

If you’ve answered no to any of those questions, your first point of call should be fixing it.


Next, make a list of people who have positively engaged with your last few email sends.

Don’t worry if it’s only a handful of your entire database - these are the contacts that are going to engage with you how you want.

Now create your best email yet and shoot it into their inbox.

This is going to get your engagement rate back on track and improve how Inbox Service Providers (ISP) and anti-spam services view you as a sender.

Armed with an improved engagement rate, it’s time to start introducing some of your less engaged contacts back into your list.

Start with a small batch of your newest contacts and send another email.

If it goes well, and opens and clicks increase from the original email, then add in another batch of recipients for your next email. Repeat this, as long as engagement isn’t dropping and you’re cleaning out your list, until you get to contacts who haven’t engaged in 12 months or longer.

Let’s be honest, they’re probably in no rush to start listening to your emails anytime soon so don’t waste your time!

Once you’ve completed your list, suppress the rest of your contacts. For best practice, make sure you set up a rule to suppress any contacts that haven’t engaged with your content in the last year.

You can always come back to these suppressed contacts… but that’s a blog for another time.  

Deliver the goods

*wipes beads of sweat from forehead*


Well that was a little longer than expected, so thanks for sticking with me. Hopefully you now have everything you need to boost your deliverability rates and get in front of more of the right people.

It’s easy to fall into bad habits, especially with something like email that has been around for years. But it’s super important that we stay on top of our game and consistently optimise the way we do things.

Next time I’ll be chatting best practice when writing and creating an email.

Make sure you subscribe below so you can see it hot off the press!

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