Sell to Win

Email deliverability: A practical guide for sellers and marketers

Jack Virag
Growth Marketing Manager, Nutshell
Jack Virag
Growth Marketing Manager, Nutshell
A hand reaching for a bundle of arrows.

“Oh, your email ended up in my spam folder” is what email marketers and salespeople hear in their nightmares.

Emails only suffer from deliverability issues for a few reasons and all of them are bad.

If your emails are ending up in your recipients’ spam folders it means that your sales and marketing are having no impact. And if no one sees your emails, it’s just a (short) matter of time before your pipeline starts to feel it.

What is email deliverability?

Email deliverability is the ability for your emails to actually end up in the target recipients’ inboxes. Most domains have good email deliverability, which means their emails typically end up where they’re supposed to go.

Some organizations, particularly ones that send a lot of sales and marketing emails, might find their emails are undeliverable or ending up in spam folders—which begs the question: What determines an email’s deliverability?

The first factor affecting email deliverability is the content of the email itself. Email servers (like Gmail) do their best to ensure that emails in users’ inboxes are pertinent and relevant, and not just spam.

There is a list of email spam words that, when found in the content of your email, will decrease its odds of ever making it to the recipient’s inboxes. Words like free, act now, Venmo, (seriously) and limited time have been identified in enough spammy emails that most email servers will automatically put them in the recipients’ spam folders or will even block their delivery outright.

The other factor is your sender reputation. If spam or low-quality emails historically originate from your email address, you’ll be penalized, and future messages might not make it to inboxes as they should.

What’s my sender reputation?

Sender reputation is also known by a bunch of other names like sender score, email reputation, delivery score, etc., but they all describe the same concept: A sender reputation is a score that exists to inform mail servers about the quality of mail coming from your domain.

If someone marks your email as spam, your sender reputation goes down. If no one ever opens your emails, your sender reputation goes down. Your sender score is largely determined by qualitative data about the way recipients interact with your emails.

Email sender reputation is tracked by numerous sources, including ISPs (like Comcast), individual email providers (like Gmail), and third-party sources (like SenderScore).

Pro tip: You can check your sender reputation at data security sites like Barracuda or Trustedsource.

Why does sender reputation exist?

The concept of email deliverability exists to prevent spam, and protect users from it. From the perspective of an email client, it’s your responsibility to not only protect your users’ privacy but also create a better email experience by filtering out undesired content.

🙁 Not-so-fun fact: An estimated 85% of all emails are spam emails. 

Things that inhibit email deliverability:

Your own sender reputation can be harmed by doing the following things:

Sending lots of email that gets unopened

Details about your email messages, like whether or not they are opened, are reported against your own sender reputation. If a disproportionately large percentage of your emails never get opened, it will harm your email deliverability in the future.

When recipients mark your emails as spam

Getting a message marked as spam is a serious offense compared to just sending emails that don’t get opened. In this case, your deliverability is docked even more, because a user has to take a clear and deliberate action to mark your delivered email as spam. (It means your email actually ticked someone off.)

If enough of these offenses pile up, your emails will eventually wind up directly in recipients’ spam folders rather than their inboxes.

This can also happen on a personal basis: If I’m a reputable sender but Ben marks all my emails as spam, my emails will end up in his spam folder, but not for anyone else.

Having a confusing sender address

Recipients are also much more likely to mark an email as spam if they originate from an email marketing platform and lack straightforward routing info.

Emails sent from an improperly configured marketing platform might contain DNS records that don’t match the name of your domain, making it look to the recipient as if the sender isn’t who they claim to be.

It’s important to personalize your marketing platform’s return-path, DKIM, and SPF domains to ensure maximum deliverability. If this sounds like jargon, check out Andy Fowler’s helpful guide on how to set up DKIM, SPF, DMARC, and custom email tracking domains, as most of the knowledge is ubiquitous across platforms.

Related: How to ensure email deliverability using Nutshell Marketing.

Sending emails to a spam trap

Excerpt from Nutshell’s Lead List Purchasing Guide:

A spam trap is an email address solely for catching spammers. They look like real email addresses, but have never actually been used to send emails, and have also never been published anywhere on the web. If someone scrapes the target domain for all its email addresses, the spam trap email address gets scraped with them.

In other words, a spam trap is an email address that exists solely to catch email spammers. Spam trap email addresses can only be obtained by scraping a domain for all of its registered email addresses, which is an illegal practice. But despite being illegal, some sketchy list providers still do it and sell the email lists to unwitting sales teams.

When a spam trap receives an email, the sender’s reputation automatically takes a hit. This is why it’s important to only email opted-in recipients or people who are verifiably real.

Being included on various email blacklists

An email blacklist is a list that identifies senders (or entire domains) that are known to send low-quality and spammy emails. Blacklists are used by ISPs and email providers alike, and they share information with one another, so if you end up on Gmail’s blacklist, you’ll likely also end up being blacklist by third-party email reputation trackers as well.

Once your IP or domain is included on a blacklist, it’s difficult to recover your reputation and increase your deliverability again. Some steps you might need to take include:

  • Removing all email addresses added after a certain date
  • Adopting a double opt-in subscription process
  • Terminating a relationship with a partner or affiliate whose behavior led to the blacklisting

Winding up on an email blacklist is scary, but some email deliverability guides do a good job of explaining how to recover.

High bounce percentages

If your email bounces, it means that your email was rejected by the target mail server entirely. Emails can bounce for a number of reasons, including:

  • Spam words in the email subject line
  • Free, Act Now, Limited Time Offer, etc.
  • Invalid recipient address
  • Emailing a spam trap
  • Email contains too much HTML
  • The subject line is all-caps 😬
  • Recipient’s inbox is full (soft bounce)

Having emails bounce is normal. It happens to regular people all the time—not just companies that send a lot of email outreach. Problems with deliverability arise when a higher-than-normal percentage of emails from your domain end up bouncing. This may be symptomatic of spam practices at play behind the scenes, like purchasing dated lead lists, sending low-quality messages, or trying to send emails to addresses that don’t exist.

Conspicuously low email engagement

Email engagement, i.e. how often people open and click on your emails, gives a vague indication of the quality of your email content.

Email reputation trackers will factor engagement metrics into your own deliverability score, meaning that if no one ever opens your emails, eventually they’ll stop receiving your emails entirely.

Again, this plays back into email providers ensuring a good experience for their users. If your messages never get engagement, it’s likely that they’re not compelling or relevant, and email providers will filter them to “spam” or “promotions” tabs as they are delivered.

Email deliverability is affected by sending emails that have low open rates, but also low click rates. A low click rate—meaning recipients open the email, read the full message, and then do nothing—might be a sign that your emails have misleading subject lines that entice the users to open the email and read more before discovering that the message is irrelevant.

High unsubscribe percentages

Unsubscribes are standard in email marketing and sales—they happen all the time. Users typically unsubscribe from content when they’ve decided it’s no longer relevant, when they’ve changed roles, when they choose a competitor, etc.

That being said, the average unsubscribe rate is estimated to be between 0.2% and 0.5% and varies slightly by industry. In general, a low unsubscribe rate is good, although higher unsubscribes can be a symptom of an organization doing market segmentation in order to better target recipients who don’t unsubscribe.

However, having an alarmingly high unsubscribe rate of 20% or so might signal email providers and ISPs that apparently no one wants to be on your mailing list, and your email deliverability will suffer.


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Tips to boost email deliverability

Using the following tactics will keep your sender reputation and email deliverability healthy:

Try to get engagement

Companies that send engaging emails have no fear of losing deliverability. Engaging emails don’t just look cool, they compel the user to take an action in the form of clicks.

Deliverability is affected by email opens and also email clicks. If there is a huge disparity between these two numbers, it can actually hurt your sender reputation. The idea is that users open the email, and if the CTAs are relevant, they’ll click—meaning that an open-heavy and click-light email might not have good content or relevant CTAs.

Pro tip: Including the recipient’s name or other personalization in the email subject line can boost engagement by an estimated 26%.

The only surefire way to keep your email engagement scores healthy is to send relevant content to the right audience. This doesn’t necessarily mean that you should have hundreds of demographically segmented micro-lists, but you should certainly rule out blasting your entire audience.

It’s also a good idea to solicit replies from your audience. The idea of actually having a two-way conversation might sound crazy (think of how many newsletters you actually respond to), but it’s not against the rules. Consider asking an open-ended question at the end of one of your newsletters and watch the replies roll in.

This is what Ashanté does and it’s awesome.

Don’t overwhelm your audience

This should already be a priority for a million other reasons. Over-emailing an audience is one of the worst mistakes a company can make, and can result in users outright abandoning the brand.

Overwhelming an audience can also hurt your deliverability indirectly. There’s no hard rule on how many emails you can send to your audience, and sending too many emails won’t specifically get you in trouble. Instead, your users will just be annoyed by you.

They’ll stop opening your emails, they'll unsubscribe, they’ll mark your messages as spam, and that’s when your deliverability will begin to suffer.

The best way to keep your email audience sufficiently whelmed is to establish some basic email cadences for your brand. Product updates are great, newsletters are wonderful, but emailing your audience “👈🤠 HAPPY MONDAY Y’ALL 🤠👉” every week for no reason other than to make noise will trounce your sender reputation.

This will happen to your reputation so fast

Double-check your email lists

This is where a lot of email senders get in trouble. Building an email list is tough. It takes time, patience, and lots of good content just to get a decent email audience. Multiply that by your conversion rate, and it suddenly makes sense why companies and email senders never want to prune their lists, or will turn to third-party list vendors to secure more contracts.

But staying on top of email list management is the only way to ensure your emails remain healthy and deliverable. Email lists decay for a number of reasons. People leave companies and their email addresses expire, or maybe your company’s content no longer interests them.

List vendors are also risky. There’s no way to know which contacts on the list are healthy, or even still eligible to receive emails, and the only way to find out is to email them. And emailing a dated list with a high bounce rate will hurt your deliverability.

It’s a good idea to stay on top of email list management by manually unsubscribing bounces (if your email marketing software doesn’t do this already) and also recipients who have never opened your emails. There’s very little upside in keeping them around, and being in the habit of removing them will keep your deliverability healthy.

Exclude auto-spam words

Spam words are words that automatically subtract from your deliverability simply by existing in your content. ISPs and email providers have determined that emails with specific verbiage tend to be unsubscribed from and marked as spam at a higher rate than normal, so the verbiage itself is an automatic penalty against email senders.

Libby Margo of autopilot points out that spam words generally fall into one of six categories:

  • Manipulative: creating unnecessary urgency or pressure
  • Needy: sounding desperate or exaggerated claims
  • Sleazy: being too pushy
  • Cheap: no pre-qualifications, everybody wins
  • Far-fetched: statements that are too good to be true
  • Shady: ethically or legally questionable behavior

Spam words include verbiage such as call now, exclusive deal, free, prize, order now, get out of debt, and much more.

This doesn’t mean that emailing your kids about a cheap, once-in-a-lifetime deal on a car from Craigslist is going to make your email undeliverable. The spam-words rule mostly applies to repeat offenders, and is factored in along with email open rates, unsubscribe rates, etc., to weigh against a sender’s reputation.

Blacklisting: The worst-case scenario

Committing too many spam email infractions will ultimately end a sender on an email blacklist, which is about as bad as it sounds. Domains that have been blacklisted will find that their emails are undeliverable, and/or automatically end up in recipients’ spam folders no matter what.

Some consider this the coup de grace for salespeople and marketers who send emails for a living.

How do email blacklists work?

A blacklist is a list compiled by third-party data security organizations (like Barracuda) that specialize in monitoring and compiling email records, and is meant to be an up-to-date account of the reputations of various email senders. 

These lists are then shared with (or sold to) ISPs, email providers, and private organizations in order to keep their users safe from spam and scams.

There are multiple ways blacklists can block spam emails, for instance:

  • Google identifies an incoming email to a Gmail inbox from a blacklisted address, and the email is blocked by Gmail.
  • An ISP identifies an incoming email to a proprietary email server, and the email is blocked by the ISP.
  • A university email server has partnered with a data security firm. All spam emails are blocked by the data security firm, but furthermore all commercial communications are screened too.

What to do if you get your domain blacklisted

Being blacklisted, although horrifying, is not the end of the world. If you or your organization have been blacklisted, the first step is to determine which exact lists have blacklisted you.

You may be blacklisted from a specific organization, for instance, if your sales reps are constantly emailing its employees and getting their emails reported as spam. This will result in all of your domain’s emails to the target organization becoming undeliverable.

In this case, since it’s a private organization, it’s up to their discretion as to whether or not they feel comfortable removing your blacklist status. Unless the blacklist determination was made in error, they probably won’t.

If your blacklist designation applies more broadly—not just for a specific organization—it’s likely that you’ve wound up on one of the larger blacklists that provide sender reputation data for email providers and ISPs.

1. Figure out which organization blacklisted you

If you’re extremely lucky, you may have received a warning from a specific blacklist operator that your domain has been blacklisted. If not, a Google search for email blacklist testing tools will help you figure it out.

While there are countless blacklist organizations reporting your sender reputation, it’s possible that your email deliverability issues are only being impacted by one blacklist. Fortunately, there are steps that you can take to repair your domain’s sending reputation with just about every blacklist provider.

2. Reach out to the blacklist organization about a course of action

It will depend on your offenses and their severity, but most blacklist operators will have a simple course of action that domains can take in order to be taken off the blacklist and allow their emails to become deliverable once again.

If you’ve been working with a third-party sales or marketing service provider that has been sending emails from your domain, it is likely the blacklist organization will recommend you let them go (which is good advice.) You may also need to enable double opt-in on your emailing marketing lists in the future to ensure that you’re not emailing anyone who didn’t ask for it.

3. Commit to better email practices

Most blacklist operators will require you to take steps to ensure that you are following good emailing practices. This can mean cleaning your email lists, removing unengaged subscribers, or even abandoning your list entirely—especially if it’s one you bought from an email list provider.

This is also a good opportunity to reassess your email marketing strategy as a whole and ensure you’re not overdoing it. Email marketing should be used as a way of communicating with subscribers who are engaged—not as a means to blast a disinterested audience in hopes that it generates engagement.

Once you’ve completed these steps, the blacklist organization should expunge your domain from the list, resulting in your email deliverability being reinstated. If your emails still aren’t deliverable, it’s likely that you’re on multiple blacklists and should repeat the steps again with a different blacklist operator.

Thanks to Gioele Fazzeri for the awesome cover photo.


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