Email is a central part of the link building process. It’s how we reach out to potential link partners, build relationships and pitch our content.

But if your emails aren’t getting delivered, none of that matters.

That’s why email deliverability is so important.

In this guide, we’ll cover everything you need to know about email deliverability, including:

  • What is email deliverability?
  • Why is email deliverability important for link building?
  • Tactics to boost your email deliverability
  • How to maintain your email deliverability
  • Common email deliverability mistakes (and how to avoid them)

This is based on our almost 10 years of experience, dealing with email deliverability, navigating through the email spam crackdown in early 2024 from Email Service Providers (ESPs) like Google, and sending several millions of emails in that time. 

Let’s get started.

What is Email Deliverability?

Email deliverability is the measure of how likely a user’s email is to be delivered to its intended recipient. Basically, it is the likelihood of your recipients seeing and reading your emails.

There are a number of factors that affect email deliverability, including:

  • ISP filtering: All email providers have some form of spam filtering in place. If your email is flagged as spam, it may never reach the recipient’s inbox.
  • Spam filters: In addition to ISP filtering, many email providers also have personal spam filters that users can enable. If your email is caught by a user’s spam filter, it will also never reach the inbox.
  • Sender reputation: Your sender reputation is a measure of how likely you are to send spam. The better your reputation, the more likely your emails are to be delivered.
  • Content: The content of your email also plays a role in deliverability. If your email contains words or phrases that are commonly associated with spam, or there is some sort of repetitive pattern being formed, it is more likely to be filtered as spam.

What’s more, email deliverability is not a static thing. It can change over time, which means you need to be constantly monitoring and improving your deliverability if you want to ensure that your emails are getting delivered.

Email delivery is also different from email deliverability. Email delivery is a measure of how many emails have actually been delivered to an email inbox. So email delivery rate, is the percentage of emails that are received by the email servers of  those recipients, and have not resulted in a hard or soft bounce.

It’s possible that email delivery can be high, but with a poor email deliverability score –  meaning more of them ended up in spam.

Also, it’s important to note that there is no such thing as a 100% deliverability rate. 

Even the best senders will have some of their emails filtered as spam. The goal is to get your emails delivered to as many people as possible.

Why Is Email Deliverability Crucial For Your Link Building Efforts?

Email deliverability is of utmost importance when it comes to link building, as it is the first step to achieving success in your email campaigns. A low deliverability rate can be the result of many different factors, including:

  • Using an unprofessional email address
  • Poorly written emails that are marked as spam by previous recipientsHaving a poor sender reputation
  • Using a blacklisted IP address
  • Having a high percentage, or succession of bounced emails
  • Using a free email service provider with poor reputation
  • Sending too many emails at once
  • Using an unapproved, or badly maintained email marketing service

If your emails are not being delivered, you’re not building any links. And if you’re not building links, you’re not going to rank in Google and bring in more traffic and revenue. It’s that simple.

Besides, poor email deliverability can affect your brand’s reputation. Even if people do check their spam and keep seeing that they’re being filtered as spam, they may start to question if they should open it, and trust what’s in there.

Improving your email deliverability should be a top priority if you want your link building efforts to be successful.

What is considered a good email deliverability rate?

It’s important to distinguish between the different metrics associated with email and how many articles out there talking about email deliverability have it wrong. 

Email deliverability rate is very hard (if not impossible) to actually measure, since ESPs. Many ESPs and tools report deliverability simply as: 

number of emails sentnumber of bounced emails

But we need to go more specifically to a metric called Inbox Placement Rate (IPR). IPR is the percentage of emails delivered to the inbox, out of the total emails sent (i.e. did not land in spam). 

Validity’s 2023 Email Deliverability Benchmark Report, found that in 2022, global IPR was 84.8%. Validity was able to measure this by analyzing the data gathered from customers using their seed email addresses (Everest Seed List). The Everest Seed List is basically a bunch of email addresses that Validity owns, where customers can send test emails to. Since they have full ownership of the inboxes, they are able to see if the email landed in spam or didn’t.

There are also regional differences, as the map below shows.

Now it isn’t possible to know what our true IPR is, since there is no ‘feedback loop’ mechanism in place, where we can find out if it landed in spam or not. 

Side note: feedback loops are an old system that used to be in place at ESPs like Yahoo and AOL, but are no longer commonly in use.

However, if you can get an email deliverability score of 86% or more – then you are doing very well from an industry, and global standard.

However, in most cases if you aren’t using seed lists to test IPR, then you want to be aiming for an email delivery rate of 98% or higher to be on the safe side. The reason is simply, the more of your emails that you can get delivered in the first place, and the less bounces you have – by extension the more of those that will be in the inbox, rather than spam.

Outreach tools like Instantly.ai, will give you some sort of email health metric, and it’s primarily based on these types of simplistic calculations, which take into account the bounce rate.

How to Boost Your Email Deliverability?

If you want to boost your email deliverability, you need to ensure that your emails pass through spam filters. Here are some best practices to follow:

Benchmark your email setup

MxToolbox have a tool for checking your email deliverability. Just send an email to the test email address they provide and then check your results.

You’ll then be able to access some diagnostics and can see if you’re on any blacklists, and if there are any issues with your DNS setup.

Ideally you don’t want to be on any blacklists, and you want your DNS setup like below.

You can also analyze the email header of one of your outreach emails, using MxToolbox, or spamcheck.postmarkapp.com. Just copy the info from one of your sent emails, and it’ll give you your SpamAssassin score and list out any issues.

Choose a trustworthy sender

When it comes to email deliverability, sender reputation is key. If you’re using a free email service provider like Gmail, Yahoo or the free version of Outlook, your sender reputation is going to be lower than if you’re using a paid ESP like Gsuite or Outlook.

This is because free email providers are often used by spammers. As a result, emails from free providers are more likely to be filtered as spam, once you’re doing things at scale. A small handful of emails from a free email provider is fine as that’s a normal pattern, but don’t try to do link building outreach from a free email, as over time you will see a deterioration in deliverability.

When using the established ESPs like Gsuite and Outlook, you can piggyback off the reputation of their IP and servers. 

Using SMTP capabilities of services like Mailgun, SendGrid, or setting up your own server on a service like Bluehost are other options our company has explored. These are potential options when doing email at scale, but this starts to become complex, and probably not worth the time invested. Weighing up all options, you’d be better to stick to Gsuite or Outlook, and following our guide.

Now, having a professional email isn’t a guarantee of success either. Your sender reputation is also affected by things like the number of bounced emails, spam complaints, and unsubscribes.

We’ll cover all of these factors in more detail below, but the bottom line is that you need to be using a reputable sender if you want your emails to be delivered.

Include an SPF record

An SPF (Sender Policy Framework) record is a type of DNS record that specifies which servers are allowed to send emails on behalf of your domain.

If you don’t have an SPF record, your emails are more likely to be filtered as spam. This is because it’s easy for spammers to spoof your email address and send emails that appear to come from your domain.

An SPF record helps to prevent this through authentication. By including an SPF record in your DNS settings, you’re telling ISPs that only the servers listed in the record are allowed for emailing.

Adding an SPF record isn’t that complicated. You just need to add a few lines of code to your DNS settings.

Create a DMARC record

A DMARC (Domain-based Message Authentication, Reporting & Conformance) record is another type of DNS record that helps to protect your domain from email spoofing. 

A DMARC record tells ISPs what to do if they receive an email that fails SPF and DKIM authentication. 

The two options are to either:

  • Quarantine the email (usually sends it to the spam folder)
  • Reject the email

Creating a DMARC record is similar to creating an SPF record. You just need to add a few lines of code to your DNS settings. 

Pro tip: This is completely optional, but if you are planning to send a lot of volume, then using the DMARC monitoring feature of a tool like GlockApps, can come in handy.

If you see this percentage start to dip too low (say under 70%), then this can indicate an issue you need to investigate

Use DKIM authentication

DKIM (DomainKeys Identified Mail) is an email authentication standard that allows you to sign your emails with a digital signature. 

This signature is then verified by the recipient’s email server to make sure that the email hasn’t been tampered with and that it really came from you. 

DKIM uses public key encryption, so it’s a little more complicated to set up than SPF or DMARC. However, it’s well worth the effort because it can significantly improve your email deliverability. 

Setting DKIM authentication in Google Workspace

If you’re using Google Workspace (formerly G Suite), you can easily set up DKIM authentication for your domain. 

First, log in to your Google Admin console and go to Apps > G Suite > Gmail > Authenticate email section. 

Next, select the domain you want to set up DKIM for and click Generate new record. Google will then generate a DKIM record for you. 

Now all you need to do is add this record to your DNS settings.

Also, don’t forget to “authenticate” your DKIM record. This is how it looks in Gsuite.

Most DNS providers will have a way to do this, but if not, you can use a service like DKIMcore.

Authentication is important because it helps to prevent spammers from using your domain to send phishing emails.

Once you’ve set up DKIM authentication for your domain, all outgoing emails from your domain will be automatically signed with DKIM.

Maintain proper IP allocation

The sender score that ISPs apply to your email, will be dependent on the health of the IP address you’re sending from. This depends on factors ranging from (but not limited to): the number of spam complaints, too many bounced emails, excessive email volume or velocity of sending, or excessive use of spam language.

If you are using a reputable service from Google or Outlook, then generally speaking, you are in an IP pool which is by extension, reputable. 

TLG have consulted with the top experts in email infrastructure and deliverability, and came to the conclusion, that even when spam blacklists say that an IP address has been marked in their blacklist – it’s unlikely that the IP will have been significantly hit, if it is from a provider like Google and Outlook. These companies regularly clean their IPs, so even if its on the blacklist, it’ll be removed at some point, or be unaffected.

That’s primarily because these ESPs have controls in place where they’ll suspend the worst abusers anyway, so their IPs tend to be more trusted.

However, if you are setting up an infrastructure outside of these ESPs, and setting up your own server –  then you need to be careful about using clean IPs, and be implementing some sort of IP rotation. 

By ensuring the emails are either split across a set of IPs, or sending is switched completely to a new set of IPs on a regular basis –  it mitigates against the risk of being blacklisted, and then having subsequent campaigns landing in spam folders.

Monitor email blacklists

Following from the previous point, make sure to monitor email spam blacklists. This is primarily based on the IP address you’re sending from, and its reputation, rather than just the email address itself.

Tools like Mxtoolbox and MXRight can help you keep track of this, and flag up if you are appearing in any blacklists.

The main blacklists you want to keep an eye on are: Spamhaus Block List (SBL), Composite Blocking List (CBL), and Spam and Open Relay Blocking System (SORBS).

Smaller blacklists outside of this, are unlikely to significantly affect your deliverability. But, keep an eye on the larger blacklists, because if you start to appear on multiple blacklists and there is a snowball effect – then it may be time to switch domain and IP.

Use a consistent persona and email address

When you’re sending emails, be sure to use the same “from” name and email address each time. This helps to establish trust and credibility with ISPs.

If you’re constantly changing your “from” name and email address, it will be harder for ISPs to recognize you as a legitimate sender. As a result, your emails are more likely to be filtered as spam.

It’s also important to use a “from” name that people will recognize. If you’re sending emails on behalf of a brand, be sure to use the brand name in the “from” field.

And if you’re sending emails from your personal account, use your real name. People are more likely to trust an email that comes from a person than from a generic email address.

Lastly, headshots are really important for building trust. Always ensure to have a profile picture there. Whether it’s your own, or a persona’s headshot. 

Verify every email address you want to email

If you email unvalidated or unverified addresses, your emails are more likely to bounce. And a high bounce rate can hurt your sender reputation.

There are a number of ways to verify email addresses, but the easiest way is to use an email verification service. These services will run a series of tests on an email address to determine whether it’s valid.

If you’re sending a large volume of emails, you can use a bulk email verification service. These services are more expensive, but they’re worth it if you’re sending a lot of emails.

By verifying every email address you want to email, you can reduce your bounce rate and improve your sender reputation.

You can use services like Zero Bounce and Neverbounce to verify email addresses. Both services offer free trials, so you can test them before committing to a paid plan.

These services provide fast, accurate results and are a great way to ensure that all your emails are delivered safely and securely. 

Sadly, not all emails are “verifiable.”

Be especially aware of “catch-all emails.” That is, emails that are set up to accept any email sent to them. This type of email often has a low delivery rate and may even be considered spam by ISPs.

Email verification tools aren’t always reliable when it comes to catch-all emails. The best way to know for sure is to manually confirm the email address by sending a test email.

Even then, you should keep your catch-all emails to a single-digit figure of your total emails, preferably less than 2%. Otherwise, you could be damaging your sender reputation.

Some other ways to maximize your verified emails include:

  • Gravatar API: Check Gravatar’s database to see if the email is associated with a profile.
  • Web search: Does the email address exist on an actual webpage or social media profile? Is it associated with a blog or other online presence? This can give further confidence.
  • Google Sheet People Chip: This feature lets you add contact info to a spreadsheet and search for email addresses based on criteria like name, location, etc. 

In Google Sheets, just paste the email you want to check, go to Smart Chips → Convert To People Chip

If it turns gray, that means it’s likely to be a valid email.

Pro tip: Setting up a BIMI record

If you have the money to spend, even get your BIMI record, and become BIMI compliant.When you become BIMI compliant, your logo becomes registered with The AuthIndicators Working Group , and you’ll be able to display your official logo in the email inbox.

When a company wants to become BIMI compliant, they simply create a DNS record that includes a URL to their logo. When the mailbox provider checks your DMARC (in your “From” domain’s DNS TXTrecord), it looks for a BIMI record. That record is simply a batch of text containing the URL for your brand’s logo and information on any Verified Mark Certificates (VMC) you may have. If the records match, they display the logo. This is how large brands like LinkedIn, are able to always have their logo show up in the recipients inbox.

The AuthIndicators Working Group leads the BIMI movement, and current members of the group include Google, Verizon Media, Mailchimp, and Valimail.

However, this does cost a fair amount of money, and at last check –  it cost $124 per month, per domain, to buy the VMC from Digicert.

Isn’t the same as putting the logo in the profile pic?

Not quite. This is where the logo is done through the official channels, and ESPs like Google, Microsoft and others, will then officially “recognise” the image. When you do it this way, you will be much more likely to have the logo displayed in the vast majority of users’ inboxes. 

When done unofficially, it may still not be present with some providers, or it may just sometimes not show up. 

Also, by not doing it officially via BIMI, you don’t get the enhanced security benefits, and the brand recall that comes with it. 

It’s important to note that even if you follow the above steps, there’s still no guarantee that your emails will be delivered successfully. Some emails will bounce for various reasons (mailbox full, email blocked at server end, their mailbox has been deleted, etc. ). 

Still, by following these tips, you can maximize the number of emails delivered. And the more successful emails you send, the better your sender reputation and the higher your deliverability rate will be.

Write clean content

The content of your emails should be clean and free of any spammy keywords or excessive use of links. If you’re including links in your email, we recommend having no more than 4 links in an email, and ideally, just 1-2 at most.

And be sure to proofread your emails before you send them. A few typos here and there aren’t a big deal, but too many can make your emails look spammy.

Besides, some words are more likely to trigger spam filters than others. For example, words like “free,” “guarantee,” and “sale” are often associated with spam emails. So, it’s best to avoid them if possible.

Some other words might include:

  • Buying judgments
  • Clearance
  • Order
  • Order status
  • Earn extra cash
  • Earn per week
  • Expect to earn
  • Extra income
  • Earn extra cash
  • Earn per week
  • Expect to earn
  • Extra income
  • Home based

Hubspot put together an exhaustive list of spam trigger words to avoid. 

The best way to avoid triggering spam filters is to write clean, well-crafted emails. By writing quality content, you can improve your chances of getting your emails delivered.

Of course, the idea isn’t to avoid using words like “free” or “guarantee” altogether. Instead, it’s to use them responsibly and in an appropriate context. 

If it makes sense to use these words, do it. But make sure that your message isn’t too promotional or spammy. And keep an eye out for any terms you are using too frequently in your templates, that could trigger spam filters. 

It’s about striking a balance between creativity and avoiding potential spam triggers.

Don’t over format your emails

Keep your HTML code to a minimum. Too much formatting can also lead to your emails being blocked as spam.

It’s best to stick with plain text or basic HTML. Doing so ensures that your emails are displayed correctly and don’t get flagged as spammy by filters.

Avoid excessive use of images, bold or italic sections, and colorful text. 

Also, make sure to include the appropriate alt attributes for images. This will ensure better accessibility and deliverability for your emails.

While you can’t always avoid using URLs, keep in mind the following tips:

  • Avoid excessive hyperlinking: Try to keep your hyperlinks to a minimum. If possible, use “naked” URLs, as they are trusted more by spam filters.
  • Use images only if necessary: A rule of thumb is to keep your image usage to one image per email, max, and only if it makes your campaign more valuable and effective – for instance like a GIF or meme. It may impact deliverability, but is worth doing if its required for the campaign and improves response rates.
  • Keep your signatures simple: Bells and whistles, such as emoticons and animations, may seem like nice touches, but they can also flag your email as spam. So keep it simple.

From an email deliverability standpoint, these tiny changes won’t impact on a low scale. But, on a larger scale, they can have an effect. 

Small, incremental changes can go a long way in your link building efforts. It’s all about understanding the basics of email deliverability and applying best practices to ensure success.

Tips to Maintain High Deliverability Rates

Now that you know how to improve your email deliverability, let’s take a look at some tips on how to maintain high deliverability rates.

This isn’t a comprehensive list, but it should give you a good starting point.

1. Personalize Your Emails

When you’re sending emails, be sure to personalize them as much as possible. Include the recipient’s name in the subject line and body of the email for example, and you can also include other personalization details, such as their location, company, or industry.

But, in many cases, you may need to go a level deeper with your personalization. For example, at the start of an email to just show you did your research (but making sure its relevant to the intention of the email.)

The more personalized your email, the more likely it is to be opened and read.

The more people open and read your emails and reply –  the better your sender reputation will be. And a better sender reputation means improved email deliverability.

2. It’s the Subject Line, Stupid

Your subject line is the most important part of your email. It’s what determines whether people will open and read your email or whether it will be relegated to the spam folder.

Your subject line should be clear, concise, and to the point. It should also be relevant to the content of your email.

And, most importantly, it should be interesting. If your subject line is boring, people won’t bother opening your email.

Some best practices for writing effective subject lines include:

  • Keep it short and sweet: The ideal subject line length is between 6 and 10 words.
  • Make it relevant: Your subject line should still be relevant to the content of your email.
  • Use numbers and symbols: Numbers and symbols can help to make your subject line more interesting. For example, “10 Tips for Effective Email Marketing” or “5 Ways to Improve Your Email Deliverability.”
  • Be personal: Personalized subject lines are more likely to be opened and read. Even small hints of personalization, like referencing the lyrics of a particular artist they like or  mentioning a recent event they participated in, can go a long way.
  • Use emojis sparingly: Emojis can be effective in some cases, but use them sparingly. Too many emojis can make your subject line look spammy.
  • Focus on what’s in it for the reader: Your subject line should focus on what the reader will get out of reading your email. For example, “a resource that boosts email deliverability 300%.”

Ultimately, the goal is to write a subject line that’s interesting, relevant, and personal. By following these tips, you can improve your chances of getting your emails opened and read.

3. Don’t Send Too Many Emails

One of the quickest ways to trigger spam filters is to send too many emails. If you’re sending a lot of emails, be sure to stagger them out over time.

Sending a few emails each day is better than sending a bunch all at once. This will help to improve your sender reputation and, as a result, your email deliverability.

Most outreach automation platforms have built-in features that allow you to stagger your emails. For example, BuzzStream allows you to set a “pace” for your outreach campaign. This pace ensures that your emails are sent out over a period of time, rather than all at once.

Lemlist allows you to set a “frequency capping” for your emails. This feature ensures that you don’t send too many emails within a certain period of time.

Pitchbox also has a feature that allows you to limit the number of emails sent in a period, and they do email drip feeding by default. This helps ensure that your outreach campaigns stay within email service provider guidelines, and it follows a natural looking pattern.

Ensure that your outreach platform of choice has similar features to help you avoid sending too many emails at once.

The idea is to strike a balance between sending enough emails to get the attention of prospects and not sending too many emails, which could trigger spam filters. 

This might get a bit tricky when you have quite “broad strategies” and need to reach a lot of people to scale things up. In this scenario, consider balancing your emails across 2 or 3 email accounts and spreading them out over multiple days.

Services like Lemwarm, Instantly.ai, and WarmupBox can help you “warm up” your email accounts before you start sending automated emails. This is especially important if you’re using a new email address or domain name for your outreach campaigns. 

Doing so will help to ensure that your emails don’t get flagged before you even get started. 

4. Simply Write Damn Good Emails

This one may seem obvious, but it’s worth repeating: write damn good emails. That time you spend writing and perfecting your email is well worth it.

Many people try to beat the system by sending mass emails with little to no personalization. But, as we’ve already established, personalized and relevant emails are more likely to be opened and read.

The best way to boost and maintain excellent deliverability is to play by the rules: take the time to write quality emails that are relevant and interesting to your recipient.

Some things to consider include:

  • Subject line: As we’ve already discussed, your subject line is the most important part of your email. So, take the time to write a good one.
  • Personalization: Take the time to personalize your email. This can be as simple as including the recipient’s name or other personal details.
  • Content: Your email should be well-written and free of grammar and spelling errors. It should also be relevant to the recipient.
  • Signature: Be sure to include a signature with information that adds credibility (e.g., your company, title, address, etc.). This  helps build trust with your recipient.
  • A clear, obvious benefit: Your email should make it clear what’s in it for the recipient. If you don’t know what’s in it for them, you shouldn’t be emailing at all. Emailing people with irrelevant content may backfire on you, hurting your reputation in the long run.

These are just a few things to keep in mind when writing your emails. By taking the time to write quality emails, you can improve your chances of getting a response – and, as a result, boost your deliverability.

Conclusion

Email deliverability is vital for successful link building. Poor email deliverability can result in your emails being sent to spam, or even worse, bouncing back entirely.

Keeping your email deliverability high is essential for maintaining a successful link building campaign. Hopefully, this guide has given you some helpful tips on how to do just that.