The Ultimate Guide To Email Deliverability for Sales Pros

Email delivery is the silent workhorse that powers prospecting campaigns. Yet it’s often overlooked. This post breaks down what email deliverability is and why it matters.

Dan Moran

Successful cold email prospecting relies on a lot of things going right.The subject line needs to capture attention. The message needs to resonate. The CTA must be compelling. Leads need to be targeted properly, and there needs to be enough of them.Many sales pros believe the formula for success stops there.

Yet this view only paints half the picture. It leaves out a crucial component that could make or break your campaigns.Email deliverability.

Deliverability is the silent workhorse that powers successful email prospecting. It’s the key that unlocks more pipeline from your outreach.

Yet it’s also one of the most overlooked factors in a cold email strategy. And that’s a mistake. The truth is, no matter how carefully you've honed your messaging, no matter how irresistible your CTAs, none of it matters if your email doesn't land in your prospect's inbox.

Deliverability is one of the most misunderstood elements of cold email—and also one of the biggest opportunities.

This guide will break down what email deliverability is, why good deliverability is mission-critical, how to test it, and how to set up your outbound email programs the right way to optimize for success.

What is Email Deliverability

Email deliverability is the ability of an email to successfully hit the intended recipient’s inbox.

In the context of outbound sales, it’s a measure of whether your cold emails are going to your prospect’s inbox or being flagged as spam or bouncing back.Sending and receiving emails is second nature in modern business. But lifting the lid on this seemingly simple and intuitive process reveals a complex system designed to keep your inbox free of potentially harmful spam.

You don’t need to understand the intricacies of email service providers. Or what all the acronyms mean.

But it’s beneficial to have a basic knowledge of how email actually works so you can spot, diagnose and fix deliverability issues—specifically around two things: sender reputation and email authentication.

Sender Reputation

Just as a salesperson's credibility influences potential buyers, sender reputation significantly affects where your emails end up.

Internet Service Providers (ISPs) gauge this reputation through various factors, such as the quality of your email content, the rate at which recipients open your emails, click-through rates, and the number of spam complaints you receive.

Email Authentication

In the digital era, where fraudulent activities are rampant, authentication proves that an email coming from your domain is legitimate.

When we’re talking deliverability and authentication, these are the big 3 protocols:

SPF: Sender Policy Framework (SPF) is like the bouncer for your inbox, checking the ID of the emails trying to come in to make sure whoever’s sending them are who they say they are.

DKIM: DomainKeys Identified Mail (DKIM) is an authentication method that checks for a digital signature or key. It confirms the sender is legit and detects forged or altered addresses.

DMARC: Domain-based Message Authentication, Reporting and Conformance (DMARC) is the final boss. It provides domain-level protection to prevent unauthorized use and email spoofing.Email providers will automatically check all this stuff in the microseconds between you hitting send and your email (hopefully) reaching your recipient.

What is a good email deliverability rate?

A good email deliverability rate is typically considered to be above 95%.The rate is calculated by the number of sent emails that reach your intended recipient’s email client versus the number that bounce back.However, that doesn’t mean your emails have reached the inbox. Emails that go to the junk folder have still technically been delivered, but just not to where you wanted. It’s important to take your email tool’s deliverability rate with a grain of salt, unless you can see exactly where your email ended up.

Why is email deliverability important?

Email deliverability is far more than just making sure your emails go where they’re supposed to—though that is super important, too.Poor deliverability has implications that can affect your entire organization’s ability to communicate online.Speaking with OneShot customers, we’ve heard stories of CEOs unable to send updates to investors and senior sales reps having their proposals blocked because their sender reputation and deliverability was damaged by irresponsible sending practices.

The potential impacts go even further:

Impact of poor deliverability

  • Blocked emails: Recipients who deem emails spam can block the IP address from which they’re sent. All future emails sent from that IP to the recipient will bounce.
  • Flagged spam: If enough people mark a particular IP address as spam, email services can automatically block that address.
  • Tarnished sender reputation: Each infraction chips away at your reputation—both at an IP address and domain level—which ISPs and email clients use to determine whether to allow your emails through.
  • Domain damage: Each infraction incurred by anyone with an email address tied to a particular domain can damage the overall reputation of the domain.
  • SEO: Domain ranking and reputation is one of the key factors used by search engines to determine whether your site is trustworthy and therefore appropriate to be listed in search results.

The damage done by mass cold emails

Modern prospecting practices are a major culprit to poor email deliverability.

Burdened with enormous targets and enabled by email sequencing tools, SDRs frequently send automated, identical emails en masse to unsuspecting prospects.

Servers pick up on this behavior, assume it’s a bot sending spam, and treat it as such. Alternatively, recipients can manually mark a message as junk—and it only takes a handful of these spam reports to seriously damage a domain’s reputation.

We’ve covered what can happen next. Domain damage. Interruptions to critical communication. Your company’s reputation as a legit business is put into doubt. Not good. You can read more about why we say you should never buy email marketing lists.

So how can you test your deliverability? Let’s dig into that next.

How to Test Email Deliverability

It’s important to regularly check your email deliverability is up to snuff. There are a couple of different ways to test deliverability.The first method is also the simplest: send test emails.

Send sample emails from the email you’d like to test to different addresses with various email providers like Gmail, Yahoo, iCloud, and Outlook. Are your test emails landing in the inbox, or are they going to the spam or promotions folder?

There are also tools available for more comprehensive testing. and MxToolbox are two examples of apps that will evaluate the health of your email for free.

These tools will check your SPF, DMARC, and DKIM records to make sure you’re validated, yet they’re a little light on what to do if one of these parameters isn’t scoring well.

To get a detailed report of your email health and actionable tips on fixing any issues, try OneShot’s free email health and deliverability tool. You’ll be able to see:

  • If you’re authentication protocols are set up correctly
  • Whether you’re on any blacklists
  • How to fix any potential issues

To grab your report, send an email to and we’ll reply with a detailed report.

11 Strategies to Improve Email Deliverability

Now you know what email deliverability is and why it matters, let’s turn to tactics to improve it.Here are 11 actionable strategies for improving your team’s email deliverability.

Always send cold emails through an alternate domain

If there’s one thing you should remember from this article, it’s this:Never prospect from your primary domain.

That way if you do incur any penalties from sending lots of emails or receiving too many spam reports it won’t affect your company’s domain health or reputation. It’s also a safe way to test and experiment in a risk-free manner.Here’s how to do it:

  • Buy one (or several) domains similar to your primary domain
  • Set up a couple of accounts under this new domain

For example, at OneShot our primary domain is yet the domain from which our reps prospect is These alternate domains link back to the primary should someone happen to type it into a web browser.Many companies buy multiple domains related to their brand as a defensive strategy to avoid competitors gaining an advantage. There’s a good chance your company already owns a bunch, so it’s worth checking with your IT person/department to see if you can use one to prospect with.It’s also important to note that the alternate domain you use to prospect needs to have the SPF, DKIM and DMARC records properly set up.

Rotate mailboxes

Alongside sending through an alternate domain, it’s also a smart practice to rotate through several mailboxes.For instance, if I were to prospect using both the and mailboxes, I can theoretically safely send twice as much outreach.This strategy allows you to spread the risk of damaging your sender reputation across multiple mailboxes, rather than concentrating it on just one.Using different mailboxes can also facilitate A/B testing of your email content, subject lines, and send times. This can provide valuable data to help optimize your cold email campaigns.

Warm up mailboxes over 30 days

One of the gravest mistakes novice prospectors make is setting up a new account and immediately firing off hundreds or thousands of emails.

This approach is sure to land you in spam.

Millions of email accounts are opened every day. Email providers are very good at detecting which accounts are being used by real people and which are spamming bots.

Email warming is the process of taking a newly minted email account and “warming it up” by sending signals to email providers that this is a legit account. It’s the process of gradually increasing the number of emails sent from a new email address or domain to build a good reputation with email service providers.

There are two main methods for warming up a new email account:

  1. Manual warm-up: Once your new inbox is set up, start emailing teammates, subscribing to newsletters, and responding to emails you receive. This generates natural and authentic engagement signals for your inbox.
  2. Use a warm-up tool: There are tons of tools on the market that will automatically warm up a new inbox for you. The process is the same, but it’s usually carried out at a larger scale.

Regardless of the method you chose, it’s best to warm up a new account over 30 days to be sure you’ve provided email providers the right signals for a good sending reputation.

Mailbox throttling

Restricting the volume of emails sent each day is a crucial aspect of maintaining good email deliverability.

Overwhelming email providers with a flood of emails from a single address could raise red flags and potentially categorize your account as spam. When you send too many emails, especially from a new or lesser-known email address, providers may think you’re spamming and you could be penalized.

This can lead to emails being directed to spam folders, or even your address being blocked entirely.

A good practice is to send no more than 30 emails per day per mailbox.

This gives you the best chance of keeping your sender reputation intact and your emails landing in your prospect’s inboxes.

Verify your email and your domain

We’ve already discussed the importance of authenticating the domain you’re sending from.

Simply put, if the domain you’re sending from does not have a DMARC, DKIM, and SPF record, a big chunk of your cold emails are going straight to spam.

Use the tips and resources above to test your domain and make sure these protocols are in place.

Remove spam trigger words from your emails

Email providers flag certain words they identify as fraudulent or malicious.

They’re built to identify terms that typically overpromise or artificially inflate a positive outcome to coax readers into forking over sensitive information. Terms like “buy,” “double your…” “free,” “act now!” and even greetings like “dear…” can trigger the filters.

These examples are a very small sample size, for a more exhaustive list check out this list of 394 email spam trigger words.

Tools like OneShot can also help you identify which words of your emails have the potential to land your email in the spam folder.

Best practice is to either remove spam trigger words entirely or use them sparingly and within context.

Optimize your subject lines

While your subject line won’t directly affect deliverability—unless you cram them with spam words, in which case you’re likely headed to spam—they do affect whether or not your email is opened.Open rates are one metric that email servers look for to determine whether you’re a reputable sender.

There is myriad advice for writing subject lines that get people to open emails. We’ve found these three best practices the most helpful:

  1. Keep your subject lines short, between 1–3 words
  2. Make them look like an internal email
  3. Highlight one specific problem, example “low reply rates”

A/B testing is one of the best ways to quickly identify which subject lines get you a higher open rate on your emails.

Monitor for low open rates

Certain metrics are indicative of overall performance and worth keeping a close eye on. As mentioned above, open rate is one.Your open rate is like a proxy for deliverability, and it’s important to understand what good, and poor, open rates look like. For cold emails:

  • 70%+ is excellent
  • 50-69% is solid and acceptable
  • <40% there could be an issue

The issue could be as benign and easily fixed as a bad subject line. Or the low open could be indicative of something more serious going on, like problems with deliverability.Closely monitor any emails and campaigns that are slipping below this threshold. If they do, turn them off and look into what’s going on.

Plain text only—remove images, links, and tracking pixels

Excessive links, images, tracking pixels, and other complex elements in emails can negatively impact deliverability.

These elements can often trigger spam filters. Also, emails full of images and custom code may not render properly across all devices and email clients. Meaning your message may be illegible.

When cold prospecting, best practice is to send plain text emails. They will format the same way across any device, and there are no links that may be deemed suspicious.

This simplicity enhances the deliverability and readability of your emails, improving their effectiveness.

But, there’s a catch: no tracking.

Of course, the downside to this is the limited visibility into email performance. With no tracking, you won’t be able to observe the detailed performance of your campaigns. No open rates. No click rates. No view counts.

However there is a strong argument to be made that deliverability is of greater importance than tracking, and you’ll ultimately know how your campaigns are performing due to the number of replies you receive.

Bonus tip: Replace the unsubscribe link in your cold emails with a P.S. asking a recipient to ask to be taken off your list. This not only removes the link, but prompts a reply which can start a conversation.

Personalize each email

Personalization isn’t just important to make your message more compelling to your prospect. It’s critical for deliverability, too.When identical emails are sent to several recipients, email servers can flag this activity as spam or coming from a bot. There are a couple of tactics to make each email you send slightly different to keep them off your back.

  • Spintax generators (spintax = spin + syntax) slightly change the structure of what you’ve written so no two versions are exactly the same
  • Custom variables, which are built into most email sending tools, allow you to add unique details like someone’s name or company
  • Personalize each message so it’s unique to the recipient.

The last one is the hardest. Especially when you’re sending hundreds or even thousands of cold emails. Personalization at scale used to be an oxymoron; and impossibility. At least until AI entered the chat.

Today, sophisticated AI can conduct deep research on a prospect and use the information it uncovers to automatically generate highly personalized outreach. And it can do this hundreds of times, without getting tired.That’s what we’ve built at OneShot. If you want to see it in action you can see a demo right here.

Verify your data

Each time a mail is unable to be delivered, it’s a hit to your domain.

Sometimes the reason an email wasn’t delivered is simply because the email address isn’t authentic, or no longer exists.It’s important to stay on top of the cleanliness of your prospect data to ensure your campaigns are only going to real, active email addresses.

How to Implement Deliverability Fixes

After reading all this you may be thinking, can I really fix all this stuff?

Some of it’s simple, and as a sales pro should be right in your wheelhouse—fixing subject lines, for example.But mailbox rotation? Email throttling? Validating SPF and DKIM records.You’re right in thinking that these aspects are outside the expertise of the sellers on your team. A little help here goes a long way.

Work together with your IT or marketing team/person

Now you know the business impact of good email deliverability, it should be easy to make the case to call in some reinforcement.

Your IT team/person should be able to help set up the more technical elements of deliverability, and test and understand what needs to be fixed.

Marketing also spends a lot of time ensuring deliverability is optimal. You may find they’ve already laid a lot of the groundwork that will help make the sales team’s campaigns successful.

When you win at email deliverability, you win at outbound

Deliverability is critical to outbound sales success.

You can optimize your sales team’s emails, offers, CTAs, and subject lines all day long. Ramp activity till you’re blue in the face. But if your messages aren’t going where they’re supposed to, it’s all for nothing.

Armed with this info, you can now test and fix your team’s email deliverability.

It may well be the biggest win to your outbound strategy this year.

If you want to check the status of your email deliverability, send an email to and we’ll reply with a full email health report.

And if you’re ready to put your entire outbound motion on autopilot, check out how OneShot can help you do it.

Dan Moran

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