The Email & CRM Vault

Next Level Email Marketing & Deliverability Secrets You Need to Know

Written by Beth O'Malley | 10/2025

 

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Whether you’re a seasoned email marketer, CRM manager, or technical marketer, you probably feel like you’ve heard all you’ll ever need to hear about emails.

From open rates (I go deeper into why the concept that ‘email success ≠ opens and clicks’ in my Biggest Myths in Email Marketing blog) to content ‘hacks’, or subject line mantras and templates…

When you’ve heard one bit of b*llshit about email marketing, you’ve probably heard it all.

Disclaimer: I’ve been at this for a while now, and I’ve sent a lot of amazing emails and also made plenty of mistakes – the thing is, in the 12 years I’ve been in the industry, I’ve learnt that following ‘best practice’ without any additional context is usually more likely to hold you back than boost you forward.

It’s those small, foundational things that matter most.

So, what the hell can you do when you’re already seasoned with your email marketing efforts, but you want to do more?

Here are the advanced email marketing & deliverability secrets you need to know that most people don’t (that actually matter!).

 

ARC (Authenticated Received Chain)

Authenticated Received Chain is a protocol that preserves your email’s authentication results (SPF, DKIM, DMARC) across forwarding and intermediary steps. 

Why does this matter? Well, not all mail passes directly from sender to recipient. Which means that SPF, DKIM, and DMARC alignment failures can occur, and your messages aren’t delivered.

Meaning that even though the original sender (you) is legitimate, they can fail DMARC.

This is especially relevant for B2B forwarding, internal company forwarding, and mailing lists – without ARC, your meticulously authenticated email could still get rejected or land in spam when it’s passed along the chain.

One thing to note here is that ARC doesn’t solve everything, unfortunately. It depends on the trust of ARC sealers/intermediaries to be effective. If intermediaries aren’t trusted or even properly configured, ARC won’t be enough to save things!

 

Priming/throttling 

Priming, throttling, whatever you want to call it, there’s a key principle I want you to keep in mind: don’t blast thousands of emails at once.

Start with your most engaged subscribers and slowly widen your scope to less active subscribers in controlled phases.

“But why, Beth?”, you say? Well, your inbox providers are watching your engagement like hawks. Too many negative signals (spam complaints, mass deletions, non-opens), and your emails quickly go from inbox to promotions to spam.

That’s what we call engagement degradation, and it can happen quickly. Before you know it, your emails are all landing initially before being banished to spam.

What can you do to avoid engagement degradation? Firstly, you want to do what I mentioned above and send in small batches, starting with your high-engagement subscribers.

Secondly, utilise timed intervals to monitor your performance in real time, monitoring negative engagement signals such as non-opens, deletions, and spam reports to adapt where needed.

And finally, always ramp up your volume slowly instead of all at once; otherwise, those negative engagement signals will be all you’re seeing when reviewing the data.

 

Bulk Sender/ISP-Level Requirements (hidden rules)

Do you know your forwarder or ISP (Yahoo, Gmail, Outlook, Apple, BT, etc) rules?

Probably not. A lot of senders don’t read the rules about:

  • Maximum acceptable spam %
  • Matching IPs/hosts
  • Unsubscribe ease
  • Consistent sending patterns
Let’s look at Google’s sender rules as an example:

  • Always give recipients an easy way to unsubscribe (if you send more than 5,000 messages per day, your marketing and subscribed messages need to support one-click unsubscribe)
  • Headers should only include one email address
  • If you send large amounts of email, you are recommended to send at a consistent rate, start with a low volume and increase slowly, and regularly monitor server responses, spam rate, and the sending domain’s reputation.

Long story short, you need to go beyond just sending “clean content”. Review the rules so that you know the sending behaviour you need to follow to stay on track.



Value Exchange in Every Email

Every email you send is a transaction with your subscribers.

And since your subscribers are giving you attention, trust, and even their data, the least you can do is give them something useful.

It’s not just a “buy now” situation; you need to make the value you’re providing clear in every email that you send.

The simplest way to view this is that you’re nurturing a relationship, and if that relationship starts to feel neglectful, it’s a one-way ticket to dropped engagement and your mail provider punishing you.

 

Emails Get Auto-Deleted (or Filters Crush Inactive Mail)

Spam filters don’t really care what someone’s reasons are for leaving your email unopened.

Which means that there’s a good chance their ruthlessness will result in your emails being auto-deleted after a period of time… making them redundant.

Providers are also pretty choosy with the space they’re willing to give you in the inbox – unopened emails are too costly at scale to be worthwhile keeping.

If your emails are relegated to unopened territory, people might never unearth them later down the line.

That’s why consistent engagement and nurture matter so much more to your email strategy than ‘just sending’ does.

 

Design & Layout Can Affect Placement

Deliverability isn’t just about the technical elements; the design is just as important in how inbox providers judge your message.

You’re probably already suffering from the common pitfalls that hurt your inbox placement:

  • Image-only emails (or heavy images with very little text)
  • Bloated or broken HTML
  • No accessibility considerations (no alt text!)
  • Oversized templates
These may seem like minor issues, but they add up quickly. If we were doing a “nightclub test” on them, your email would look suspicious from the outside and be bounced right out of the club.

The best practice to get into is to balance text and image, keep HTML clean, ensure accessibility is a priority, use alt text, and test rendering before sending!

 

Engagement Decay 

Not to make your mail provider sound like a sentient being, but it does hold a memory of how you engage your subscribers.

This matters because it means that when you switch from sending emails regularly to disappearing entirely, your reputation suffers, and your standing in the mailbox goes on a steep decline, too.

“Consistency is key” might be an overused phrase in marketing, but that doesn’t make it any less relevant.

If you suffer from engagement decay, even your legitimate, authenticated campaigns will start from a much worse position. 

Consistency and rhythm are just as important as the actual content you’re sending out, so consider this carefully before overcommitting to a schedule you can’t keep.

 

Ignore the Deeper Layers and They’ll Quickly Stack Against You

I’m not saying that subject lines and content don’t matter (duh!).

But when it comes to laying a foundation for your email marketing to thrive on, it’s the overlooked and infrastructural elements that really do matter.

If you invest in your email infrastructure, list hygiene, and advanced tactics, you can rest easy that all of the hard work you put into your emails will result in them landing exactly when and where they’re supposed to.

If you want someone who does all of the finicky bits behind the scenes - ARC, priming, deliverability troubleshooting, etc - then talk to me. I’ll do the messy stuff so that you don’t have to! 



 

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RE:markable is the weekly email about emails. Dropping the latest email marketing news, updates, insights, free resources, upcoming masterclasses, webinars, and of course, a little inbox mischief.