The Ultimate Guide to Email Deliverability

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Email marketing continues to play an important role in digital marketing. May people prefer email to other types of communication. It’s a marketing channel where it’s easy to build relationships and increase revenue. Email marketing is more complex than writing an email and sending it to a list. There are many challenges and one of those is getting your email to the inbox.

It’s known as email deliverability.

What is email deliverability?

Email deliverability is a term used to describe the likelihood of an email arriving in the inbox instead of the spam folder or being rejected.

For example, John regularly sends emails to 5,000 recipients. After the last email campaign, there was a sudden increase in the bounce and spam complaint rates. This indicates a deliverability problem.

Why deliverability matters

Deliverability is critical to the success of email marketing.

You’ll read advice telling you how to build a list, how to craft the perfect subject line, and how to create calls to action that readers can’t resist clicking. But if your emails are not being delivered, you don’t have an email marketing program.

According to Sendgrid, one in five emails doesn’t arrive in the inbox. That’s only 80 per cent of emails that are delivered. Some people might be happy with that, but it means that you might as well have not sent the other 20 per cent. They’ve cost you money. And likely damaged your sender reputation.

If this was happening to John, for those emails that he sends to 5,000 recipients, 1,000 emails that were never given the chance to be opened. He could have improved his results by not sending them to 1,000 recipients. There’s also lost revenue to consider. If the average revenue per email is $100, that could be $100,000 in lost sales. All the time spent building a list, designing emails, crafting message content, and optimizing landing pages is wasted time if emails don’t get into the inbox.

Why email deliverability is hard

Understandably, many people think that when an email is sent, it just arrives in the inbox. But there is a  lot is going on behind the scenes. For one, each email service puts each email through a series of tests to determine if that email should be delivered to the inbox, sent to the spam folder, or rejected. The result of those tests is known as sender reputation.

Put simply, sender reputation is built up over time and indicates the trustworthiness of your email domain.

Each inbox service has its own set of tests and calculates sender reputation in different ways.

It can be difficult to get an email that will pass all those tests.

Those tests can include:

Your email domain, the bit after the @ symbol, must be considered trustworthy.

You need to be sending emails from a reliable service.

The IP address used to send the emails must be trustworthy.

Your email has to get past several filters including spam filters.

The inbox service will consider past behaviour from emails sent by you. Past behaviour can include sending to email addresses that consistently bounce.

If you pass the tests, has the recipient identified your emails as spam? If several recipients on that service have identified your emails as spam, the inbox service may reject your emails for all recipients.

If not rejected, your email may be delivered to the recipient’s spam folder.

Once it gets into the recipient’s inbox, the recipient needs to engage with the email.

These challenges can be overcome by adhering to email deliverability best practices and making that deliverability effort something you regularly pay attention to.

Email deliverability best practices

Don’t ignore deliverability. It’s too important.

Improving email deliverability starts at the beginning and should be ongoing. This is where tracking your email metrics pays off.

Even if you have problems with email deliverability now, these best practices will help solve them.

Email authentication

Authentication checks include:

SPF: Was the sender authorised to send the email?

DKIM: Has the email been tampered with?

DMARC: What happens to the email if it fails authentication checks?

Email volume

This relates to the number of emails sent from the service you’re currently using. It’s the number of emails an inbox provider receives compared to the number of emails previously sent.

Inbox providers can see an unusual increase because of changes such as:

You’ve merged with another business and increased the size of an email list.

You have an email list that hasn’t been used for a year or more.

In situations such as these and with a large number of emails being sent, use a process known as warming up.

This is where emails are sent in small batches. Send to the most engaged readers first. This establishes a good sending reputation. Over two or three weeks, increase the number of emails being sent until you’re sending to your whole list.

Changing service providers

Your email sender reputation is linked to your service provider and IP address. If you change email service providers or move to a dedicated IP address, inbox services don’t know who you are.

If you start sending to everyone on your list without starting to build a new reputation, inbox providers will assume you’re a spammer – because that’s what spammers do.

Just like sending emails to a list that’s suddenly increased, sending from a new email marketing service or IP address needs the same warm-up process.

Sending frequency

Sometimes referred to as cadence, it’s how often emails are sent.

This relates more to recipient behaviour. If you’re sending too many emails, your readers may unsubscribe or identify your emails as spam.

Spam filters may also identify emails as spam if their algorithms consider that you’re sending too many emails in a relatively short time. An example is suddenly sending two or three emails a day. A common practice for Black Friday or Cyber Monday sales.

Send no more than two emails a week.

Email content

Content includes the subject line, preheader text and message body.

Don’t overuse spammy language and formatting.

Spammy language and formatting can include:

Notice I said don’t overuse spammy language and formatting. Someone with a good sender reputation will not be blocked because they use one spammy word in one email.

Keep your list clean

Good list hygiene will help your deliverability by lowering your bounce rates, keeping unengaged subscribers off of your list, and lowering your spam complaints.

It also helps avoid sending to email addresses that never existed or are no longer valid.

There are four simple things you need to be doing to keep your list clean:

Strive for engagement

Once your email arrives in the inbox, inbox providers pay attention to the number of recipients who take positive engagement actions.

If recipients aren’t opening your emails, that tells the inbox service that they don’t want them. Your emails will start looking like spam. Segment your lists, test and optimize your subject lines, and send targeted, relevant and timely content to your subscribers so you’ll engage them and thereby improve your deliverability rate.

Use personalisation to deliver the content each reader wants.

Watch your metrics

Metrics will give you an indication of how trustworthy inbox providers consider your emails.

It’s not always about looking for problems. Monitoring metrics relating to deliverability will show what’s working well. By knowing what’s working well, it’s easier to see when something might be going wrong.

Sometimes your emails appear to be getting through and then suddenly emails to one service are blocked. Your sender reputation can plummet overnight.

For deliverability, monitor:

The sooner you know you have email deliverability issues, the sooner you can act to fix them.

As well as metrics related to deliverability, monitor metrics that track positive reader engagement. If readers aren’t engaging with your emails, it could attract unwanted attention from inbox providers.

Positive engagement metrics include:

Continuous improvement

Maintaining a good sender reputation isn’t something that’s done once and forgotten about. Except for warming up a new IP address or email marketing service, improving email deliverability is an ongoing process. You should always be trying to improve your sender reputation.

For instance, you split test versions of a subject line. One performs one per cent better as shown by an increase in the average open rate. It’s only a relatively small increase. The big improvement comes from an increase in engagement which helps your sender reputation with the inbox providers.

How to check your sender reputation

As I mentioned earlier, there is no single place to find your sender reputation across all inbox providers. However, you can use a few tools, stats, and tips to monitor and better understand your sender reputation. And you can test your deliverability.

Some services can help you track your sender reputation. Services such as GlockApps Inbox Insights.

Some micro and small businesses may not have the budget for services like this.

For the very small business owner, there are simple ways to get an overview of how an inbox provider might assess your sender reputation.

Used together, these tools can check that:

Email authentication is correct.

The email domain or IP address is not on any major block lists. Don’t panic if you are. It’s not unusual to be on one or two low-end block lists.

The email content doesn’t contain spam indicators.

Those tools are:

Google Postmaster Tools

If you’re consistently sending high volumes of emails to Google Gmail or Workspace recipients, Google Postmaster Tools can give useful insights that include IP reputation, domain reputation, delivery errors, and more.

MXToolbox Deliverability Tool

MxToolbox is a comprehensive set of tools to assess different aspects of email marketing. One of those is the Deliverability tool. This tool will indicate whether email authentication is correct or not.

Send a test email to [email protected]. Once the tool has assessed the email, you will receive an email with a link to view your full deliverability report.

Mail Tester and Mail Genius

Like the MXToolbox Deliverability Tool, these will show results from email authentication checks. Additionally, they will identify any content that may be considered spam.

These two tools can assess emails in different ways so it’s worth getting reports from both.

Use a seed list

A seed list is several email addresses you control that aren’t part of your email domain. Create two or three Gmail, Outlook.com, and Yahoo Mail email accounts. This is your seed list.

Don’t make any changes to the default settings. Any changes could impact where emails are delivered.

To test deliverability, send an email to the seed list then check each to make sure emails arrived in the inbox.

Email metrics

Track your metrics. If there are no sudden changes in open, bounce, or spam rates, that’s a good sign that inbox providers trust your email. If the average open rate suddenly drops and the bounce and spam complaint rate suddenly increases, the cause should be investigated. Changes like these are usually due to list bombing.

Nothing is guaranteed

Any deliverability testing is an indicator of how an inbox provider might assess an email. Just because all indications are that you have a good reputation, it doesn’t mean your emails won’t be sent to the spam folder, or blocked outright.

Sender reputation will change over time. Regularly monitoring metrics is key to understanding how your overall reputation is changing.

Wrap up

Email marketing seems like it would be easy, but in reality, it’s hard, not just the deliverability piece of it but all of it. For most, email marketing is something that’s learned as you go. And that approach doesn’t always lead to the best results.

Improving deliverability won’t happen overnight but it does happen by making small changes over time.

Most importantly, your email reputation is in your control. What you do, or don’t do, influences what inbox providers do with your emails.

By using the tactics and tools presented in this article, you’ll have more control over how inbox providers assess your mail.

Let us know about your experiences with email deliverability. What tips and tricks can you add to this article?

Head over to the Atomic Education Facebook page and join the conversation.

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