Comprehensive and Detailed Guide on How to Find and Fix Email Deliverability Issues Professionally

Vladislav Podolyako
Jul 21, 2022
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When you send emails to your friends and family, you rarely worry that the outgoing messages won't be delivered. However, things change dramatically when you start working in the marketing industry and initiate dedicated email campaigns to raise brand awareness and company income. All because most messages are programmed to carry out a preset function that is closely related to your business's well-being. The more emails end up in the junk folder, the greater the company's losses will be.

That is where the notion of well-monitored email deliverability comes in more than handy. In case you still have a vague idea of what the concept stands for, why it is critical, and how to find and fix email deliverability issues with the least of efforts involved – you have come to the right place. With our dedicated deliverability guide at hand, you will forget about the spam folder troubles once and for all!

Email deliverability – a brief definition

Before you learn all about improving email deliverability scores in the most effective ways possible, you need to be aware of what the notion of deliverability stands for. To put it simply, πŸ“§ deliverability rates are peculiar stats that allow you to monitor how many of your emails go to the primary user's inbox and how many of them can't pass the spam filters and end up in the junk section. Based on the gathered information, you will learn how to fix email deliverability and avoid related problems in the future.

Is the deliverability rate significant?

If you are new to email marketing, it may seem pretty vague why you should care about deliverability stats. In fact, you wouldn't be a single vendor to neglect the damage caused by deliverability issues unless the negative toll reaches the point of no return.

Marketing success

It would be a poor idea to expect to reap the fruit 🍎 of your well-thought email campaign if your emails miss the main inbox, wouldn't they? In case half of your email list does not even open your messages, you can't hope for the sales to skyrocket. Things like that occur when the emails target a spam inbox instead of a primary folder. Thus, fixing the deliverability rate would be the only practical way of overcoming the issue.

Inbox competition

You can't hope to be the sole representative of your niche in the present-day world. The ongoing vendor competition gets fiercer by the day. However, you can get to the top of the user's inbox if you establish a solid and positive relationship with your consumer base. A proper deliverability policy comes of use in this case too.

Client behavior

The more you know about your user base, the easier it will be to trigger their interest and appeal to their needs and preferences. That is a shortcut to effective email marketing and increased sales. By carrying out a regular email deliverability audit πŸ“‘, you will be able to track the open rates, conversion, open time, and other peculiar behavior stats, which can play a critical part when you continue to adapt your marketing strategies and following campaigns.

How do you spot and fix email deliverability issues?

Whether we like it or not, it is not always clear why emails go to spam. Sometimes, when your emails don't pass spam traps, you can request blacklist data on why things like that happen. However, countless spam filters keep those matters hidden.

While it may seem like a lost cause, and you will never figure out why those mailbox providers move your emails straight to spam, primary deliverability issues should hit your to-check list. πŸ”Ž There are a few common deliverability components to investigate:

Email content problems

Professional email marketers put a lot of thought and dedication into proper email content designed to trigger the users' attention and future involvement. Yet, countless deliverability issues still occur based on inappropriate content elements. If not long ago, these were the keywords or subject lines that caused the problem. These days, the case refers to such additional email components as URLs, message patterns, image-to-text ratio, and more.

Modern spam filters are encoded to exploit fingerprinting as the primary tool to determine whether the email is going to spam. You can think of spam filters as digital detectives that inspect your message's contents on the deepest level. A faulty fingerprint can land your email campaign in the spam folder instantly. These days, fingerprints can be referred to every part of the emails. Everything counts, whether it is a subject line, theme, color, header, footer, or image βœ”οΈ.

As the system starts to analyze email content, all the located fingerprints are compared to other known fingerprints. If the filter detects a close match between your email content and those fingerprints considered spam, your messages will be instantly flagged. That is why it is a great idea to test your email before you initiate the campaign.

Folderly presents an excellent variety of tools that can help you test your email templates to avoid potential deliverability problems.

How do you test email content?

If you are new to the industry and want to keep away from all the spam traps as far away as possible, you may wonder what the journey's starting point is. Countless industry experts suggest that you start with the subject line. These are the primary points to investigate:

  • Length of the line (make sure it varies within 35-50 characters).
  • ALL-CAPS format (change it instantly if your subject lines are written in all capitals).
  • Punctuation (delete all the unnecessary punctuation marks).
  • Potential spam words (delete all the words that can trigger spam filters).

πŸ“ In some cases, fixing subject lines is all you have to do. However, you should carry out another email deliverability test to ensure your messages get into the primary inbox. In case they don't, you should proceed with the content check. There are other points to evaluate before you can move to another element. You can continue with the following tasks:

  • Delete the URL from the text if you use any. In various cases, these are the URLs blocked by the filters and not your message, per se.
  • Remove all the images if the issue persists.
  • Test the text. If that does not help, you may want to work on another, higher-quality template.

How can you fix email deliverability issues related to the content component?

One of the best ways to correct any deliverability issues that refer to content would be to run a dedicated test and inspect the received stats. However, there are general points to investigate and rule out. These are the following:

  • Bad HTML – delete all the inappropriate or unclosed tags.
  • Text to image ratio – 60/40 is the best ratio since spammers mostly use large images to 'fool' filters.
  • Link and image legitimacy – don't use any elements offered by sketchy sites and platforms.
  • IP address links – avoid them at all costs. Use URLs instead.
  • Unsubscribe link – ensure that it is provided within the email due to legitimacy laws.

Authentication deliverability issues

Why do emails go to spam if the email content is well-structured and legitimate? It would have been a lot easier to locate and fix email deliverability problems if they were reserved to a single area, but the reality is rarely that simple. Various server malfunctions can lead to deliverability drop as well. πŸ’‘ Missing authentication records, usually SPF and DKIM, are to blame.


With Folderly at hand, you can check your Sender Policy Framework and DomainKeys Identified Mail records in no time. Once the test is over, you will be sure which direction to point to improve email deliverability.

How do you fix authentication issues?

Before you continue sending emails, you must correct all the problems that an authentication report highlights. Remember that SPF and DKIM records are of utmost importance here.


Failing SPF

In case you spot some issues related to the Sender Policy Framework records, you should rush to the DNS server settings. The sending IP and the SPF record should coincide.

Failing DKIM

DKIM requires as much attention as the previous record since it can lead to delivery issues too. The central role of the record is to ensure that the sending server provides an active private key for the email. The receiving server, in its turn, will combine it with the public key held by the domain's DNS server. If you spot any process components failing, you should try and fix them straight away so that your deliverability scores improve.

Reputation-based deliverability issues

There is more than one reputation type to watch out for when working on profit-oriented marketing emails. Each reputation variation is as vital as the next. Thus, close monitoring of each is a great way to fix email deliverability fast.

Find and fix email and domain reputation issues

The following top problems that can negatively affect your deliverability scores are closely connected with the notion of the sender's domain reputation and email reputation, in general. While the issue sounds quite complex and scary, it may not be the worst problem to face as long as you approach the matter professionally.

It is not a secret that most spam filters have various up-to-date lists of suspicious email addresses. The same comes for suspicious domain lists. 🚩 Thus, if anyone with the same email/domain has used to spread spam, the filters will automatically flag you as a spammer.


These days, various mailbox providers rely on IP reputation, yet more and more popular mailbox providers stick to the domain reputation stats. Should you be interested in some practical examples, Gmail can be named as one of the email service providers relying on the sender's domain rep. Vendors who send mass emails to inactive recipients or feature a high complaint rate are regularly blocked by the mailbox provider.

How to test a sender’s email address?

Now, when you know about the underwater stones of the sender address reputation and the domain rep, you may be willing to figure out how to test those stats. Various deliverability tools can assist you 🀝 in testing every involved sender address connected to the same domain. If you find out that the same message hits more primary Inboxes when sent from a different sender email address, the IP and domain remain unaltered – the issue lies within the old address. However, if you don't see significant changes, you may want to switch to a different domain and run the same test.

How do you solve sender address and domain issues?

The simplest way to deal with a sender's address issues is to acquire a new email address simply. However, as simple as the solution may seem, it is not recommended to change the address very frequently. The primary reason is that the same address increases engagement and helps you build a trusting relationship with the user base.

In case persistent deliverability issues are connected to the domain's reputation, the quickest way to solve the matter would be to develop a new domain.

IP addresses reputation problems

If you have reached the IP reputation section, none of the above steps have proved to eliminate existing issues, and your emails are still going to spam. Should you be new to the field, you may not realize that your sending address can be connected with spamming activity in one way or another, and that brings an IP address straight to the blacklist. In the worst-case scenario, you may even be blacklisted by two or more sources.

πŸ‘‰ There are three main types of IP address reputation rates:

  • bad;
  • neutral;
  • good.

Should you hit the 'bad' category, your emails will be sent straight to the spam folder or blocked altogether. A neutral IP reputation is widely accepted, and a good reputation speaks for itself.

Very often, spam filters inspect the IP address in the first place. If the address is on a whitelist – the email contents aren't checked, and the message is delivered to the inbox. However, if the IP address is added to any known blacklist, your email can be blackholed, bounced, or marked as spam. Blackholed emails are considered the most harmful since they are packed with viruses and other malware in most cases. Such emails aren't deleted immediately, but stored, so administrators can access them should the need arise.


How do you check IP address reputation?

You can test the IP reputation in two ways:

  1. You should try another email service provider or mail server. Even if you use a personal server, it helps to test the reputation via any reputable email service provider and observe the stats. Yet, you shouldn't alter the subject line or any other email component while doing that.
  2. Another popular way to test the IP reputation would be to use an IP blacklist checker. You can figure out what to do next based on the received data.

How to fix email deliverability by correcting IP reputation?

Those who use their mailing server can fix the reputation issue on their own. Most IP addresses that end up on a blacklist can be whitelisted. All it takes is to initiate a removal request, and the blacklisting platform will evaluate it. However, if you operate through an email service provider, all you have to do is to wait until the provider delists your address. They do it regularly.

βš’ Among other things you can do to improve the reputation scores would be to cut the email volume. It would help to send your campaigns to engaged users only instead of the whole email list. Such an approach will also positively affect the decrease in spam complaints.

What if you can't improve your reputation?

Sometimes, the IP reputation can't be restored, and you should be ready to face the outcome. If that is your situation, it does not mean you should stop mailing your clients due to the mishap. What you can do is get a new IP. However, you have to understand that some spam filters may still associate the rep with the new address, domain, or both. So, you can't expect your emails delivered to the primary inbox.

Another route would be to change both the IP address and the domain (changing ESPs may be required). Yet, most companies wouldn't be open to the solution since it is impossible to leave their domain. If that is your case, you should switch the IP, get a fresh subdomain, and preset another sending address and authentication record. While that seems time-consuming, it is the best way to get results that match your goals.

How do you achieve a good sender reputation?

While perfecting your marketing emails to the point of leaving all the competitors behind, it's crucial to realize that they will always be less essential to the receiver than personal or transactional emails. Yet, your marketing campaigns must come right at the top πŸ” of the lower-priority messages. That is what a good sender reputation can assist you in achieving. A few leading practices can help you improve email deliverability through an excellent sender reputation.

Seek permission

You'd be surprised at the number of spam complaints about incoming emails people haven't signed up for. Various industry experts suggest you forget about single opt-ins and pre-checked opt-ins and aim at confirmed opt-ins instead. Such an approach will ensure that you form a base of active subscribers genuinely interested in what you sell.

Launch warm-ups

One of the most critical mistakes that email marketers often make is leaving the warm-up process πŸ”₯ unattended. You should learn how to initiate the process correctly if you are about to start mass email campaigns from a dedicated IP address. Should you start sending out huge bulks of emails, mailbox providers may view such activity as suspicious and either block you or send it to the spam folder. Neither option would be acceptable if you want to succeed in the field. That is why building up your sending volumes gradually will warm the IP up, and you will hit the inbox placement you aim at.

Authenticate your emails

A quick check will help determine if all the DNS records are intact. Should you spot any configuration issue that concerns either SPF, DKIM, or DMARC records, you should fix it as soon as possible. Without proper authentication, any reliable mailbox provider will flag you as a spammer, which is a direct way to sender reputation and deliverability drops.

Manage spam complaints

In case you don't know, you can monitor the number of spam complaints that come your way. Some mailbox providers are equipped with special notification systems that inform you about the ongoing bounce rate and user complaints. With that data in mind, you can remove the unsatisfied email subscribers from the list so that they don't get further messages from you and enhance your email performance.

Track unengaged recipients

Most ESPs have a predefined period that can determine whether a user is engaged or unengaged. If a recipient does not open your email within 6-12 months (depending on the provider), you can consider them unengaged. The more extensive the list of such clients grows, the lower your sending reputation will be. Thus, it is a healthy approach to track your open rates and remove unengaged users from your email program ❌.

Find and fix email deliverability issues through Email Compliance Laws

Another effective way to fix email deliverability would be to comply with all the email marketing laws known in the field. Some common steps can ensure you are not breaking any laws and that your spam rate does not skyrocket.

Header data

Your header info contains such extra details as the sender’s email address, subject lines, and reply-to address. Thus, if you want to abide by the laws, you should not change or alter the provided header data.

Advertisement emails

If you want to reduce the spam score of your campaign, it is advised to name your emails what they stand for – marketing offers. Should you decide to mask an advertisement under a 'personal email' mask, you will be breaching the compliance laws, and that will affect your deliverability rate negatively.

Company address

A legal sender email address is an excellent way to improve your vendor reputation and reduce the spam score. However, if you want to hit more inboxes, you should consider stating your actual mailing address in the message. These days, most reliable marketing tools provide templates that offer spare space to dedicate to your physical address.

Opt-out feature

While you may want to center your attention on proper opt-ins, the field professionals claim that an opt-out feature is as critical. The more freedom you grant your clientele, the lower the complaint rate will be, which is a direct way to legitimize your campaigns and improve deliverability rates πŸ“ˆ.

Opt-out requests

No matter how many companies introduce the opt-out features to comply with the current laws, a fair share of vendors simply ignores the incoming requests. What is more, some brands go as far as to demand a fee for closing an opt-out request. If you choose to follow either of the mentioned paths, you will be breaking the laws directly, and you can count on negative deliverability consequences to hit your campaign.

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After you fix email delivery issues, you may consider that the deal is done, and you should wait until the paying clients and unlimited purchases point your way. However, aside from a successful delivery, it is essential to ensure that your messages hit the right inbox instead of going to spam. That is where the notion of effective deliverability comes into play.

Countless issues can decrease your deliverability rates. However, most of them can be easily fixed with the proper approach applied to the existing problem. βœ… With our deliverability-programmed guide, you will spot any potential issue before it does your brand any damage. Furthermore, all the presented solutions will assist you in fixing the matter with ease and in no time!

Vladislav Podolyako
Vladislav Podolyako
Founder & CEO
Vlad’s decades of entrepreneurial wisdom and business building experience have allowed him to successfully mentor a diverse group of business owners, entrepreneurs in growing their companies. A recognized expert in the areas of transforming organizational culture and leadership development, B2B Sales, Marketing, spent more than 10 years building technology products, with a background in communication networks and electronic device engineering.

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