The EcoSend Guide: Improve your email deliverability

Conquering marketing's final frontier — landing emails into your clients’ inboxes

28 Sept 2023

It's super frustrating to spend weeks crafting excellent copy, kitted out with a juicy CTA and your latest, hard-earned testimonial – only to see your email campaign miss target and fall flat.

Soft bounces, transient bounces, hard bounces, spam blocks, the dreaded “silent discard” (we’ll get to that one later)… These are all lead balloons to your email marketing ROI.

If Email Deliverability was a time & place, it would be the Wild Wild West.

There are no hard & fast rules nor much consistency across email providers, so ensuring your emails deliver currently is more art than science.

Regardless, even if you can never guarantee 100% email deliverability, there are a few proven techniques to stack the odds in your favour.

And stack the odds we must. For nothing good ever came from an email which missed its target.

So join us, as we dive into EcoSend's Ultimate Guide for increasing your email deliverability.

Why don’t some of my emails deliver? 

Bounces 🛑

Welcome to Lesson One - those pesky bounces.

There are 3 different types of 'bounce'. Some are message dependent, such as “attachment too large” – typically a Soft Bounce. Some are marked as Transient Bounce, such as “mailbox full”.

Your Email Sending Provider (ESP) will try to resend the email according to their own schedule and determined number of times. For example, six attempts over three consecutive days.

You could also hit Hard Bounces if your recipient’s email address no longer exists. Or your sending IP may have a poor reputation, meaning the Internet Service Provider (ISP) decided not to allow the email to deliver.

The level of information you receive on Bounces will often vary according to the recipients’ inbox email providers.

And… to make things even more confusing, ESPs often treat bounces differently.

Some soft bounces will be automatically retried. Other ESPs may temporarily block a particular recipient address. Some hard bounces may trigger an address to be permanently removed from your list – all of which really depends on the sending provider you use.

“Silently Discarded” 😱

This category is one of the reasons why Email Deliverability is such quagmire.

Silent discard is essentially when an ISP blocks receipt of an email, but without marking the reason for doing so, nor hard-bouncing the email.

It's a double-whammy; your emails don’t get delivered, but without giving you any visibility or insight into the reason why. Helpful!

Some email platforms are a bit more notorious than others for silently discarding emails, Ycombinator forum has a helpful thread on this here. (NB. This is an external, public forum – the language at times in the comments can be a little… spicy.)

Spam Complaints 🙅‍♀️

Spam complaints are no joke. This isn’t just a case of compromising a Marketing campaign or two. Poor email deliverability can lead to your emails getting outright banned.

Email Service Providers (ie. the back-end platforms that actually send out your emails) are unforgiving. Anything as seemingly inoffensive as a Spam Complaint rate of 0.5%, and your ESP could decide to boot your company permanently off of their services.

It's serious business.

That means not only your Marketing campaigns out the window, but all emails set-up on that platform go too. Welcome emails, subscription update reminders, payment confirmations…

We don't want to sound preachy, but this is exactly why following best-practise is so important.

Best Practise – The DON’TS ❌

I know I'm speaking to the choir here but just in case the point needed reiterating…

… the finest copy, meticulous re-writes, sparkling landing pages, intricate Sales funnels, and (most of all) Marketing budget; all get tanked if your emails do not land in your recipients’ inboxes.

As with most things, the first port of call for finding a solution tends to be the “do not do’s”. So let’s take a dive into these first.

1) Avoid Email Marketing black magic 🧙‍♂️

Although this is becoming less & less common, some Marketeers still restore to buying email lists, or worse, scraping sites for email addresses.

Purchased lists are almost always chock full of low quality email addresses, so you’re targeting users who are unlikely to fit your ICP or even be vaguely interested in your service. Targeting them is a pointless exercise.

Worse still, because these users won’t know who you are, that makes them all the more likely to mark your emails as Spam; damaging your email reputation and future deliverability rates.

As for email scraping, this strategy is riddled with spam traps, not to mention outright illegal in many countries. Don't touch it.


Guess what happens to spammy copy? It ends up exactly where it belongs… in the spam pile.

Gone are the days of dodgy direct marketing tactics, today’s ESPs are primed to filter out suspicious looking content. Excessive use of caps-lock and exclamation points is guaranteed to set alarm bells ringing.

At best you’ll get ignored, at worst you’ll see spam complaints sent from your recipients to your Email Service Provider. In case it needs reiterating, that is very bad.

3) Avoid those trigger words 🤢

Similar to the above, ESPs are always on the look-out for ‘trigger words’ and sensitive to anything which seems remotely suspicious.

Remember the last terrible-spam-email you received? Chances are it included one of more of the following:

  • Act now!

  • Free gift!

  • 100% Results guaranteed!

  • Check inside – offer expiring!

  • You’re a winner!

You may well have crafted eloquent, non-spammy copy for your emails. But you might innocently have included a similar phrase to the 'trigger' list.

So do check over your emails with a fine-tooth comb before sending out, just to see if any trigger words slipped through the net.

4) Don’t send long or heavy messages 😮‍💨

I know you have a great product. I know you want to tell people as much as possible about it. But please don't be tempted to send lengthy emails full to the brim with attachments, images, or PDFs.

  • Don't blastout all the information about your entire platform in one email. Instead, drip-feed a Sequence through to your users over the period of a week. Not only will this increase your email deliverability, but it also gives your audience a chance to digest your content at their own pace.

  • For images, remember that too many large images causing long email loading times. This can trigger ESPs to recognise your messaging as spam.

  • Instead of attaching PDF files, upload them to your site then add a link as a CTA within the email copy. That’ll decrease email load time and increase deliverability rates. Not to mention, the less heavy the email, the better for the environment.

  • Be careful with embedding video. Many Inboxes block video embeds by default. Instead, add a play button in-front of an image for recipients to click. This can then take them through to a separate page hosting your video online.

5) Don’t be generic 🙄

Addressing your users with generic terms. Phrases like ‘Hi friend’, fall straight into the trigger word category. Plus, you don’t want to give the reader the impression they’re just one of a million users receiving the same email blast-out…

Instead, personalise your content to address your readers by name. Ideally, connect your email platform to a solid database of users, to make sourcing relevant information easy.

Better yet, go a step further. See if you can add references to the users’ specific industry, or perhaps even company name.

This enables you to send email with a personal touch, at scale; while safeguarding deliverability and engagement.

Best Practise – The DO’S ✅

1) It’s all about active subscribers, not total subscribers 💡

It's great to build up your email list over time, and I know there's a ton of hard work involved in that. But chances are some of those email addresses might now be outdated.

Sending campaigns to expired emails will give you hard bounces each time, and hurt your email deliverability rates over time. So it's time to let go.

Just like house-keeping, you need to be tidying your email list on a regular basis. Ensure only active subscribers are receiving your messaging, and keep your email reputation in the green.

Noticed that a segment of your list haven’t opened an email for months? Seeing the same email address bouncing from your last couple of campaigns? Delete them asap!

2) Watch out for ‘grey’ users 👀

Graymail is another phenomenon of email deliverability. Some users may come across your site with a vague interest to learn a bit more, and sign-up to your newsletter. But over time, their interest fades or their focus changes, yet they still continue to receive your emails.

But emailing this segment is not good for your email reputation. Nor your Marketing ROI.

These users aren't interested in receiving your communication, they just never got round to unsubscribing.

They’re either ignoring each email you send or worse, your messages are just filling up their spam folder.

This is why it’s SO important to monitor user analytics closely. If you see a section of your list hasn’t returned to your site for months, or never signed-up for a trial, it’s likely your messaging is falling on fallow ground.

Don’t treat these users like active users; see if you can re-engage them first. Try to entice them back to the site with a time-limited offer, for example.

If that fails, consider sending a “Permission Pass” email. This will ask if users wish to continue to receive your communications – if they do, great. They're active and you can continue to message them. If they don't confirm, then keeping them is just a vanity metric.

Better to remove them from the list to keep your deliverability high and engagement metrics healthy.

3) Send your emails from a person, not your company 🙋‍♀️

No one likes receiving an email from a ‘do not reply’ address.

Sending your users an email from a no reply or generic address is like approaching a stranger at a cocktail party, talking at them for five minutes, then walking away as soon as they try to get a word in.

Your emails should be engaging your users. And that’s a two-way communication.

You want to offer your recipients the chance to reply and interact with you at every possible turn. Including your email sends.

So get rid of the no replies or contact@’s and send your emails from a real human. You’ll increase your open rates, increase user-engagement, and it’ll be a boost to your email reputation.

4) ESPs prefer regularity 🗓️

If you can, try to stick to a regular sending schedule. ESPs are sensitive to spikey or erratic sending behaviour, as this mimics typical spam activity.

Instead, try to retain the same cadence of sending out your campaigns.

If you have a Weekly newsletter, aim to send it at the same day & time each week. Not only will your email deliverability thank you, but clients will get habituated to receiving it at that moment. Meaning they are more likely to be ready to open and read it.

Every industry differs on best sending times, so run a few experiments and dig into the click metrics to find which timing works best for you.

5) Double opt-in 🔒

We're getting a little controversial now.

Perhaps you're thinking, ‘But Chris, if I add double opt-in won’t that create friction in my sign-up process? I don’t want to miss out on valid sign-ups!

Well, here’s the thing, if a user can’t be bothered to click one confirmation email to subscribe to your content, how serious really are they about your business?

Chances are, they’re the kind of reader who’d end up not engaging with your content in any case. And they’ll probably end up in your Graymail list.

So, although adding double opt-in could marginally decrease your number of total subscribers, I’ll bring you back to point one of this section. You shouldn’t care about total subscribers, you should care about active subscribers.

You want to filter for users who are actually going to open your emails, read your content, and engage with your product or service. Double opt-in is a good system to filter out time-wasters.

6) Send targeted, personalised messaging, at scale with EcoSend 🎯

Email Marketing has evolved over the past years.

Gone are the days of loading up thousands of users into an email-blaster, and shooting out a generic email.

Today’s user is much more sophisticated, and requires more sophisticated outreach from you.

One of the best ways to ensure good email deliverability is to ditch the email-blasts and swap-in highly segmented, targeted messaging.

Don’t send the same message to everyone, filter your users according to:

  1. Who they are?

  2. How they are engaging with your platform?

  3. What previous messages they have engaged with?

For the former, great examples are grouping users according to Company Position or Company Size. After all, the comms you send to the Founder of a startup should be very different to the comms to an Enterprise Marketing Manager.

In addition to user characteristics, you want to meet your users where they are in the journey with your product. This increases the likelihood of users engaging with your messaging consistently, because it will be relevant to them.

Got a cohort of users in their first week with your platform? Set up an automated onboarding sequence.

Better still, segment your users according to how they have engaged with your previous campaigns.

Filter for users who opened your latest Webinar announcement, but didn't click the link to register. You can then target them with a time-limited offer to nudge them over the line.

You can also filter which users in your contact list haven't opened any of your campaigns for months. These are definite 'Graymail' users, and it's time to send them that break-up email.

6) Monitor your Campaigns with EcoSend Insights 📈

Imagine there was a way you could monitor the performance of all your email campaigns, with real-time data showing you changes in key metrics like Open Rate, Click Through Rate, as well as proactively flagging any uptick in dangerous metrics like Bounce or Spam Complaint Rate?

Wake-up, your dream is a reality 😉

With EcoSend Insights you have a full dashboard displaying all your campaigns key metrics at the click of a button.

This means you'll easily be able to identify which campaigns are performing well, which are performing poorly, and changes to your user-base's engagement over time.

You can then take action accordingly to update your campaigns and email list, to give your emails the best possible chances of high deliverability rates.

What does all that mean over time? Good open rates, low spam complaints, and good email reputation ✅

Thanks for reading!

Phew, that was a lot of ground covered! We hope you've found this guide helpful and you are ready to go off with actionable tips to improve your email campaign deliverability.

As always, if you have any questions or would like to book in an email deliverability consultation with one of our team, just reach out to us here!

About the author

Chris Walkling

Chris Walkling

Customer Success

About the author

Chris Walkling

Chris Walkling

Customer Success

Grow your business sustainably

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Grow your business sustainably

Get the EcoSend Weekly newsletter — inspiration, helpful tips, and a good giggle, every Friday.

Grow your business sustainably

Get the EcoSend Weekly newsletter — inspiration, helpful tips, and a good giggle, every Friday.

The email marketing platform for better business

Win new customers, send better email, and make the planet better with every campaign.

  • Free Email Templates

  • Smart Segmentation

  • Lead Forms

  • Automated Campaigns

  • Automatic Offsetting

  • Team Sharing

  • HTML Email Editor

  • Multi-channel Campaigns

  • Drip Campaigns

  • MailChimp Import

  • Zapier Integration

  • Powerful API

The email marketing platform for better business

Win new customers, send better email, and make the planet better with every campaign.

  • Free Email Templates

  • Smart Segmentation

  • Lead Forms

  • Automated Campaigns

  • Automatic Offsetting

  • Team Sharing

  • HTML Email Editor

  • Multi-channel Campaigns

  • Drip Campaigns

  • MailChimp Import

  • Zapier Integration

  • Powerful API