Rapid Growth

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Why are your emails going to junk? Email deliverability made simple

Jake Higgins

Head of Growth

Email remains a powerful way to communicate with your customers, but staying in their inbox requires some work. This is especially true as you scale your sending volume.

Key Takeaways

  • Setting up email authentication is vital

  • Manage your IP & Domain reputation

  • Avoid the spam traps

  • Email certification can help

  • Run tests to increase engagement

Email Authentication

Firstly, you must have your email authentication set-up correctly - this is often handled by a technical lead. Email authentication verifies that an email is actually from you or your business. It is often thought about like a digital signature.

Spammers and phishers take advantage of the way email was originally designed, in order to create fake emails from legitimate email addresses. Internet Service Providers (ISPs) such as Gmail, use email authentication to help determine if something is spam.

There are four primary methods of authentication:

DomainKeys Identified Mail (DKIM), Sender Policy Framework (SPF), Reverse DNS and Domain-Based Message Authentication, Reporting and Conformance (DMARC)

For further information on how to technically set-up this up, you can read more here.

Managing your reputation

There are two types of reputation:

(i) IP reputation

Email is sent from IP addresses, and it’s advisable to create a dedicated IP so you can better control your IP reputation. You will not be impacted by other senders’ bad practices. There’s a good write-up by SendGrid here, on the choice between a shared IP or dedicated IP.

(ii) Domain reputation

Domain reputation is now being used in combination with IP reputation by most ISPs, but we expect there to be a full migration over to domain reputation soon. Trashing your brand’s domain reputation has serious consequences, underlining the importance of best practice email sending.

What determines your reputation?

  • The level of engagement your emails received (opens, replies, forwards, clicks)

  • The volume of emails marked as spam or complaints to the ISP

  • The organisation’s inclusion on different blacklists

  • How often the organisation hits an ISP’s spam tram

  • The number of hard bounces (eg. invalid email address) or soft bounces (eg. recipient inbox full)


Managing your reputation

Separate IPs & Domains

We advise our companies to set-up a separate sub-domain and IPs for their marketing email (eg. newsletters) and transactional email (eg. receipts). Your transactional email will have very high engagement and it’s vital to not risk its reputation as those communications are critical to the customer.

Avoid the spam traps (what is a spam trap?)

The ‘pure spam traps’ are used by ISPs to catch the spammers, the only way this can end up on your list is if it was obtained without permission.

But the term ‘spam trap’ is also used to describe email addresses in your list that were obtained with permission. An email address that is no longer in use will generate hard bounces that hurt your reputation, especially if you keep sending to them.

There are also ‘internet bots’ that run automated scripts on the internet, and can sign up for your email lists. These will often not be legitimate email addresses causing your hard bounce rate to increase.

One method of beating the spam traps is to ‘Double opt-in’ your email sign-ups, this means that once an email address is entered onto your site, the user will have to take the additional step of verifying that email address from their inbox.

This helps radically reduce the issue of spam traps, but also increases the quality of your email list. You will avoid users mistyping their email address (or actively giving a fake email) and therefore causing hard bounces. But importantly, you’ll have a clean email list of people who actually want to receive your mail - naturally, this also increases engagement rates.

But if you don’t want the extra friction of the verification step, you have the option of ‘Single opt-in’ i.e. the user enters the email address once and is automatically added to your list.

If you want to take this approach, we advise these simple steps:

(i) Use clear language at the point of sign-up, make sure the user understands what they will be receiving and why

(ii) Actively segment your list to weed out users who do not engage with your email (eg. if not opened in the last 90 days)

(iii) Make sure you’re using an email service provider that automatically removes unsubscribes and bounces (or that you’re managing this via your application)

(iv) Make the unsubscribe button more prominent to avoid spam reports

Another option for Single opt-in is to add the google CAPTCHA tick-box at the bottom of your sign-up form. By ticking ‘I am not a robot’, you stop any internet bots entering your list and causing hard bounces. This would reduce the pressure to segment out inactive users as frequently.

You can also use the below to reduce hard bounce rates from users mistyping their email address during single opt-in sign-up flow:

Email engagement

High-quality, personalised email content will dramatically help your engagement. Test and refine constantly, sending different subject lines and body content to see what your audience respond to best.

Include the sending domain in the links, as URL shorteners such as Bitly are used by spammers - if you want to track your links you can add utm parameters onto the end of your url. Generally, don’t include too many links and images especially if the amount of text content is low.

There are also particular words and phrases that trigger spam filters eg Free, Now, Time Limited - there’s 438 known words to avoid in this article. That should help you get a feel for what the ISPs are looking for, but note that it does all depend on the context those words are used. Common sense override is recommended here, just ask yourself if your copy reads like a scammer.

Email certification

If you feel you’ve still got problems or are scaling your email send volume rapidly, we would suggest speaking with ReturnPath, who have a direct relationship with the ISPs and can add a certification stamp onto your mail. This indicates that you’ve met the standards required by ReturnPath for that certification. In the onboarding process they will audit the way in which you collect email addresses, and let you know what needs to change to meet the certification standards. For example, you may need to make it clearer to the user what to expect from your emails or add an unsubscribe link.

However, email certification is not a silver bullet solution. For example, Gmail are said to not give much weight to any certification be that ReturnPath or any other provider.

In conclusion

When your email service provider (ESP) reports back a metric for amount of emails delivered, it’s important to realise that this is a delivery of emails to the ISP only. This does not describe email delivery to the inbox.

Poor engagement is often the best indicator of email deliverability problems, and starting with best practice saves you significant problems in the future.

Companies such as Dyn or SendGrid offer tailored email deliverability advice and solutions, which can be very effective for large volume email senders.


Jake Higgins

Head of Growth

Jake was the first employee at Property Partner, which he helped grow from 0 - 10,000+ customers. That was following numerous growth roles at startup and large technology companies, taking time in-between those to teach Digital Marketing & Business Fundamentals at General Assembly. Jake is a fellow at the New Entrepreneur Foundation.

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