A Complete Guide to Deliverability for Email Outreach

If your outreach doesn’t land in the recipient’s primary inbox, then everything you worked on goes to waste.

Your email copy gets buried.

The research you put into finding the recipient and setting up your sequence was a waste of time.

The lead is effectively lost, even though they didn’t even get a chance to see your pitch.

This is how critical email deliverability is. You can’t ignore it, and you can’t expect it to be solved by the tools you are using. 

This guide will help you get your outreach deliverability from 0 to 100.

What is email deliverability

Email deliverability, or inbox deliverability, is the ability of an email you send to land in the primary inbox.

For an email to get delivered, two things can’t happen:

• It can’t bounce, and
• It can’t be classified as spam/promotions.

Why deliverability should matter to you is, therefore, a rhetorical question. If your email isn’t delivered or lands in spam, it won’t be opened or read.

Deliverability is critical for anyone sending emails at scale, from marketers sending newsletters to salespeople pitching prospects. That is because when you’re sending hundreds or thousands of emails, email providers apply extra scrutiny to your messages, and maintaining a high deliverability rate is much more difficult.

Why deliverability is a challenge for email outreach

For anyone new to sending emails, the concept of deliverability may be confusing: why would email servers reject emails from legitimate senders?

One key goal for email service providers like Gmail or Outlook is to protect their users from spam. And they don’t know that you’re not a spammer until you’ve consistently proven yourself to send emails that people want to read.

When your email account or sender domain is new and wasn’t used for email outreach before, email providers pay close attention to what you’re sending and the engagement you’re generating.

Furthermore, your pitch is typically your first interaction with the recipient’s inbox. There is no history of positive engagement. A clean slate.

Why some emails bounce or land in spam

To achieve a high email deliverability rate, you must understand why some emails never reach their intended recipient.

If you’re looking for a quick explanation, then deliverability is primarily determined by the engagement your email sequences generate—as long as you have some technical basics in place.

If you consistently get a high rate of positive replies, deliverability shouldn’t be a problem. On the other hand, if all you get is bounces, spam complaints, and unsubscribes, email servers will treat your emails like they treat spam. 

In other words, replies are deliverability’s best friend, while bounces and spam complaints are its worst enemy. And again, you do need a technical foundation for this to be true.

Let’s look at these issues in more detail.

Reasons why emails bounce

Most people have seen a bounced email when they misspelled someone’s email address. Hence, many professionals believe that a bounced email indicates the email address they used was incorrect.

But that is not the case.

You may see emails bounce due to technical factors, or because email providers don’t think your emails are good enough to be delivered.

Here’s a complete list of reasons:

• Your mailing list contains non-existent email addresses
• Your sender reputation is low
• You have missing or misconfigured email authentication protocol records
• Your domain or IP is on a blocklist
• Your message looks like spam
• Your sending volume has spiked
• There are issues with the mailboxes of your recipients

If you see a high bounce rate and want to lower it, read our guide on preventing bounced emails.

Reasons why emails go to spam

Like with bounces, there are many reasons why emails go to spam. And it’s not necessarily because they look like known forms of scam. Legitimate emails often land in spam, too.

Here are reasons why emails go to spam:

• You are not authenticated as the sender (email authentication protocols)
• You’re listed on email blocklists
• Your email accounts are not warmed up
• Your daily sending volume is too high
• Your sending volume suddenly spikes
• Your message looks like spoofing
• Your emails aren’t personalized
• Spam-related words are used in your message
• There are shady links or attachments in your message
• The structure of your email looks odd
• Your email is too long
• Recipient marks it as spam
• Recipient previously unsubscribed
• You consistently get low engagement on your outreach
• Email violates internal policy

For more on avoiding the spam folder, read our guide to why emails bounce.

How to diagnose email deliverability issues

Knowing if your outreach lands in the primary inbox is tricky. 

Email marketers have it easier than outreach senders. Since they can use servers optimized for mass-scale sending to opt-in subscribers, they benefit from feedback loop mechanisms that let them know when someone reports their emails as spam, and even if they land in the spam folder.

But this isn’t feasible for outreach senders. With a low sending volume and multiple sender domains in rotation, implementing these feedback loops mechanisms simply doesn’t make sense.

Instead, here is what you can do to assess your outreach deliverability:

Monitor deliverability-related metrics

When sending email outreach, you can’t know which emails landed in spam or which recipients sent spam complaints, but there are other metrics you can monitor:

• Bounce rate
  Every bounce is a hit to your deliverability, so you should keep bounce rates as low as possible. Staying below 2% is the industry standard.Tools like Hunter Sequences automatically monitor bounced emails and report your bounce rate.
• Open rate
  Disclaimer: Our data indicates that tracking open rates may harm your reply rates—tracking pixels themselves damage deliverability. That said, open rate can tell you about how often your emails land in the primary inbox. If you’re tracking it, then it can be a proxy metric for deliverability.
• Reply rate
  Finally, if you’ve been sending email outreach for a while and have a baseline average reply rate, then it can help you spot deliverability issues. If the email content stays the same but reply rate suddenly drops, then it’s likely that your messages are no longer reaching the primary inbox as often.

If you’re sending outreach with Hunter, monitoring these metrics is easy, even if you’re using multiple sender domains and dozens of mailboxes.

Use inbox placement tests

Another way to test your deliverability is to use an inbox placement test.

Inbox placement tests are designed to check if a given email campaign will get successfully delivered to your recipients. 

Inbox placement testing tools let you send a test email to a test inbox or multiple inboxes. Then, the test tells you if your email was delivered and whether it landed in the spam folder, promotions, or the primary inbox. 

Your recipients are bound to use various email providers – not just Gmail and Outlook but also less popular providers. Consequently, an inbox placement test should have inboxes set up across a wide range of email providers to test your deliverability thoroughly.

My favorite inbox placement testing tool is GlockApps. It’s a paid tool that offers a wide range of testing services. 

For a simple deliverability assessment, use Glockapps’ Manual Test.

GlockApps lets you select from a wide range of email providers, even covering many country-specific providers from outside the U.S.

Then, it provides a list of email addresses set up with the providers of your choice so you can send them a test email.

Use an IP reputation checker

Knowing your sender reputation is tricky because it’s not an objective metric. 

Every email provider uses different methods and data to calculate your reputation, and Gmail is the only provider that lets you actually check what your reputation with Gmail is (if you’re eligible to use the Postmaster Tools—most outreach senders won’t have the sufficient sending volume.)

However, there’s one tool you can try to get some information about your IP's reputation: SenderScore.

SenderScore collects data from various sources (unfortunately, they’re undisclosed) to estimate the IP reputation of your email server.

The free report also provides a high-level overview of metrics related to sender reputation, like the ratio of filtered messages sent from the IP, or the number of contacted spam traps.

Remember that SenderScore’s reputation metric is not the same as internal metrics email providers use.

How to solve deliverability for your outreach emails

Now that we’ve covered the things that affect email deliverability, here is a guide to solving it.

Start with technical basics

A technical foundation goes a long way. You typically set things up once when you set up your sender domain and email accounts, and don’t need to worry about it afterward. But these small steps are the low-hanging fruit of email deliverability.

For a quick check on key technical factors, use our email deliverability checker.

Get a separate sender domain for email outreach

Don’t send email outreach from domains you’re using for other purposes.

If you make any mistakes and your domain's reputation drops, it won't impact your ability to get emails delivered in other scenarios.

Get a separate domain for email outreach.

(First, check if the domain you’re buying isn’t blocklisted—if it is, you’ll waste your time and money.)

Only send email to verified recipients

Email verification is the single best way to reduce your bounce rate, which in turn affects your deliverability.

Verification is cheap or free if you're sending outreach at a low volume, and it lets you easily discard invalid recipients that will bounce every single time.

Monitor email blocklists

Getting on an email blocklist is easy—all it takes is one spammy outreach campaign. But getting unlisted is difficult, and sometimes impossible.

Still, you should monitor email blocklists to understand your overall deliverability for each domain you use to send email outreach.

Being listed on a third-party blocklist doesn’t automatically mean your emails won’t hit the primary inbox: major email providers use their own blocklists that we can’t inspect. But it’s a warning sign.

If you’re interested, here’s a deep dive into email blocklists.

Don’t use a freemail account to send email outreach

The cheapest way to send someone an email is to use a free email account like @gmail.com or @outlook.com. 

This may work if you only send a couple of emails, but if you’re serious about outreach and email deliverability, you need a proper custom email account.

Sending from a custom domain delivers a +108% higher reply rate than freemail (5.2% vs 2.5%).

The lesson here is straightforward—do not use a freemail account for email outreach.

Use a reputable email service provider

Not all email providers are the same.

We recommend using tried-and-tested ESP services like Google Workspace and Outlook 365 for their scale and reliability.

Plus, your recipients are also likely to use these services, which may positively impact your results. While we haven’t been able to measure this, there’s some consensus in the email outreach space that matching your recipient's email provider increases the odds your email lands in the primary inbox.

Using different, possibly cheaper services puts your deliverability at risk, because it’s your email provider—not your outreach platform—that physically sends your emails.

Don’t track email opens

Our internal data is clear on this. Email sequences that track open rates get fewer replies.

This isn’t ideal, but it’s the reality. Open rates are incredibly useful for testing different subject lines and, as we covered above, they are useful as a proxy metric for overall deliverability.

But if reply rate is the north-star metric, then you shouldn’t track email opens.

Implement a daily sending limit

A tell-tale sign of spamming is that a spammer targets every email address they can possibly find, and so they are looking to send as many emails as possible.

On the other hand, legitimate senders should take great care with who they’re targeting. And if you’re carefully selecting your recipients and personalizing your emails, it doesn’t makes sense that you’d send thousands of emails per day.

Email providers expect to see a daily sending volume that looks like a human is manually sending emails—even if you’re using something like Hunter to automate the sending.

And to help you automatically target a large list of recipients while giving your campaigns a natural cadence, Hunter implements daily sending limits (which you can modify) for every email account used to send your sequences.

Send great emails

The second, perhaps more critical component of deliverability is what you actually send.

Not being a scammer isn’t good enough for email providers to let all your emails through the gates. 

You need to send emails that are relevant, personalized, and trustworthy.

Why does it matter for deliverability? Simply because the main enemy of deliverability is a spam complaint, while its best friend is a positive reply. Sending sequences that aren’t annoying and generate meaningful engagement will make ESPs much happier to see your emails incoming.

Use narrow targeting

No matter how smooth your email copy is, outreach can’t land if it’s sent to the wrong person.

There’s only one way to solve this:

You must be intentional about who you’re targeting. The people you email should match your ideal customer profile. Simply put, they must be in a position to be interested in your offer.

Targeting is never fully solved, and reality may falsify the ideas you have about your ideal audience, but one thing is clear: the better you can target your email outreach, the better the reply rate will be, which will do wonders for your deliverability.

Send valuable, relevant content

Next, you need to send emails that are design to generate “yes”. A common strategic mistake when people create email sequences is an expectation to do anything other than start a conversation.

Think about the maximum value you can provide for your recipients, and the minimum amount of effort they would need to reply. This will provide a good starting point for coming up with email content that’s genuinely valuable.

Personalize your emails

Spam is not personal. At best, it’s using personalization as a gimmick that doesn’t make the message truly personal.

If you’re serious about email outreach and deliverability, personalization is table stakes.

At a bare minimum, you should be using custom attributes like your recipient’s name and company name—which you can easily get if you prospect in Hunter. This shows that you’ve done basic research and you’re not sending this by mistake.

What’s even better is when every email you send is a slight variation on your pitch. Traditionally, outreach emails achieved this using spintax: randomly choosing a variant of a word or a phrase for each message. Nowadays, AI does a better job “spinning” your email copy, taking into account every piece of data you have on each of your recipients. 

If you use Hunter Sequences, its AI Writing Assistant does exactly that: it looks at prospect-level attributes to apply slight contextualization to your pitch.

If you can spare a little more effort, consider manually editing some of your messages based on the manual research you conduct on your leads.

Don’t use spam-related language

There are some words and phrases that you should generally avoid in email outreach because they are associated with spam. While spam filters are getting increasingly smart with AI, many still use these infamous phrases when calculating the probability that your message is spam.

To avoid this, use the spam checker inside the Sequences editor.

Don’t send excessive follow-ups

Following up without adding anything of substance is what annoys recipients and makes them report you as spam.

The key to following up is to make every message count. The broad strategies you can use when sending follow-ups are:

• You can change your ask. For example, instead of checking for interest with your recipient, you can ask if there’s anyone at their company that might be interested in your pitch, or you can simply use a different, softer call to action.
• You can add value: send a report, add data to your original email, or talk more about the benefits of your offer.

Keep your content professional

Sending email outreach, you need to balance persuasiveness with being professional. Adding humor may help get your recipient’s attention, but if you overstep the boundaries, it may also get you reported as spam.

A good practice is to always read your sequence out loud and ask yourself: Would you say this to a stranger in person? 

Add an unsubscribe link

Letting your recipients unsubscribe may prevent some of them from hitting the spam complaint button. It’s a way for anyone that didn’t care for your emails to express their frustration.

Hunter Sequences automates that for you.

Stick to plain text

Finally, email outreach is not the same as email marketing. When you send messages to people that opted in, you can use HTML to style your email content. 

With email outreach, sticking to text is likely to yield better results. Spam filters don’t react well to excessive styling, which is often associated with spam.

Can email deliverability fluctuate?

Deliverability isn’t set-and-forget. One email sequence that generates too many spam complaints, and your high deliverability becomes a thing of the past.

Then, there are changes implemented by email providers themselves. In the recent years, Gmail and Outlook have implemented strict rules for senders, requiring email authentication for all mass senders, and observing a rigid spam complaint rate threshold of 0.3% (for Gmail recipients.)

It’s not something that you should have to worry about on a daily basis. But you definitely should monitor your key metrics on a regular basis and react if you see them change.

In Sequences, you can use the Reporting view to monitor all email metrics over time.