Improve Inbound Email Deliverability with This Checklist

Vladislav Podolyako
Jan 28, 2021
Reading duration
17 min

Delivery rates show how many emails land in your recipients’ inboxes, end up in spam folders, or get blocked by Internet Service Providers (ISPs.) Numerous companies make the same mistake of ignoring these issues, which results in losing clients. On the contrary, progressive businesses regularly analyze their email statistics. For instance, Wok to Walk managed to raise its delivery rates by 7.7% after conducting quick research. 

It’s essential to continually enhance deliverability despite the changes in algorithms and other technology updates. Fortunately, modern progressive techniques allow for better campaign results. We’ve collected the most efficient solutions to improve your email deliverability and minimize possible adverse outcomes. 

1. Conduct DNS setup authentication for the domain name 

Email authentication is essential for maintaining a solid online reputation. Not only does it provide your brand with a clear identity, but it also adds credibility to your company. 

Use your domain hosting providers, such as GoDaddy, AWS,, Cloudflare, and DigitalOcean for domain authentication. Your task is to prove that no one else has access to it; otherwise, your delivery rates might suffer. 

We’ve prepared a few tips on how to authenticate your messages the right way:

  1. Enable Sender Policy Framework (SPF) to succeed and add Domain Keys Identified Mail (DKIM) to see MX and SPF records.
  2. Come up with an authentication record on the above-mentioned protocols and hit “publish.”
  3. Make a roadmap of all the IPs from which you send newsletters for authentication.
  4. Adjust your server to use a DKIM signature for outbound emails, provided that your MTA possesses the correct software implementation.
  5. Use testing tools, such as Policy Record Tester, to evaluate your records.


Put in some work to do authentication the right way and enjoy better campaign results. 

You can find an example of each DNS record below:

Google SPF record
v=spf1 ~all” 

Sendgrid DKIM record | MX |”

Reject DMARC record 

BIMI record 
v=BIMI1; I=https://yourlogourl.svg”

Google MX record 

2. Check your email deliverability, inbox placement, postmaster, and other feedback from ESPs

Email delivery rates greatly depend on the number of complaints your messages get from dissatisfied users. ISPs estimate your email reputation to decide whether you aren’t likely to send spam. Thus, it’s essential that your new ESP supports feedback loops to stay notified about the complaints. 

Feedback loops notify senders that their audience considers their messages unsolicited. In other words, progressive ISPs provide senders with permission to collect negative feedback from dissatisfied recipients. Those are the loops (FBLs) allowing to see who made a complaint and why. A standard Abuse Reporting Format (ARF) is applied to provide feedback to a sender in an automatic message containing the email that caused an adverse reaction. 

Please note that you can easily get this data from Microsoft, AOL, and Yahoo (see a comprehensive list of ISP reference tables at Word to the Wise). As for Gmail, only an ESP can access its FBL since it does not support the ARF format. Such an approach allows for the quick removal of irrelevant subscribers that used to contribute to increased spam rates. Additionally, make sure to conduct a comprehensive analysis of the feedback your ESP provides. For instance, evaluate your inbox placement and postmaster. 

Have a look at the following table showing a typical cycle an email goes through and possible outcomes that depend on different feedback types. 

Additionally, make use of predictive analysis. Use the knowledge of your clients’ spending patterns to increase the ROI. Predicting their behavior will also help you facilitate customer retention. Simply design a sending schedule based on such data, choose a sufficient number of messages, and select the right time. 

3. Maintain appropriate dedicated IP allocation for inbound email outreach

Once the number of newsletters, transactional emails, and other daily inbound messages to warm leads exceeds 25,000, you are supposed to indicate a dedicated IP. Adding it is essential for the expansion of your campaigns, so maintain an appropriate email infrastructure. 

Make sure to fix IP address issues. They are potentially dangerous since they affect your sender score. At the same time, it is possible to fix most of them. You just have to convince ISP filters that your IP address can be trusted. Thus, if you’ve noticed any suspicious signs, stop sending messages until you’ve corrected them. Otherwise, your delivery rates might go down. 

Campaigns that target warm leads usually involve dedicated IP addresses. So check if all your emails are legitimate for both ISPs and your recipients. Furthermore, make sure whether all of your contacts are real. Then, find out if your content fulfills their demands and whether they look forward to your emails. 

4. Start building trust with SPF

Sender Policy Framework (SPF) performs the function of email authentication. It decides what mail servers are trustworthy enough and can be involved in sending emails from your domain. You can compare the domain to a new vehicle. Before you take your first drive, you have to prepare insurance, which is a valid SPF record. It will help you get along with spam filters and obtain the necessary authorization allowing you to “drive.”

A sender policy framework can significantly improve your online prestige and enhance delivery rates. If you get along well with an SPF, it will likely boost your credibility among your target clients' servers. The latter tend to check whether your domain is reliable. An SPF can help you prove that your IP is fine and, thus, you possess a trustworthy domain allowing for legitimate campaigns. 

5. Optimize your inbound opt-in process

Deliverability greatly depends on the way you collect contacts. We recommend you to optimize this process. Double-check whether your subscribers are fully devoted to your content. The thing is, only dedicated receivers will keep your delivery rates high. If your audience isn’t interested in what you are sending, your messages might end up in junk mail. Consequently, you may experience trouble with ISPs since they can consider you a spammer. Thus, it is better to apply double opt-in to reduce the possibility of a mismatch and nurture the existing leads. 

What is more, you should filter entry email signups. The thing is, not all signups are equally valuable. For instance, contest entry email lists are likely to contain numerous invalid addresses because people are usually in a hurry while filling out signup forms. They often enter the wrong details, which negatively affects delivery indices. Therefore, it’s crucial to filter your signups, especially if you tend to resort to giveaways or contests to update your client database. Otherwise, you might experience high bounce rates leading to labeling your IP address as “naughty” and banning it. 

6. Keep your email copy free from spam words

Consult with a list of spam words while creating subject lines and the message. Email providers tend to check them automatically. Thus, even if you come up with the best idea, but it contains a prohibited word, your campaign isn’t going to be successful. Additionally, avoid using ALL CAPS and exclamation points and try not to sound pushy. 

Furthermore, make sure that your HTML elements correspond to accepted standards. The thing is, the correct text structure is essential, so check your links, headings, lists, and other items. Also, don’t embed excessively large images in your email copy to avoid loading problems.

List of email spam words

  • free offer;
  • 100% satisfied;
  • risk-free;
  • congratulations;
  • cancel at any time;
  • consolidate debt;
  • 100% free;
  • urgent;
  • income from home;
  • luxury;
  • no cost;
  • giveaway;
  • number one;
  • pure profit;
  • additional income;
  • increase sales;
  • be your own boss;
  • request now;
  • fantastic offer;
  • potential earnings;
  • guaranteed;
  • winning;
  • fast cash;
  • subscribe for free;
  • hurry up;
  • special promotion.

We don’t recommend using these phrases in your subject lines because filters usually mark them as spam.

7. Write quality content and email copy 

Focus on creating useful materials that will suit your target readers’ tastes and solve their problems. We suggest that you design a checklist to find out whether your content satisfies the parameters in your ideal customer profile. Each of your messages should be relevant to your leads. If they don’t meet your subscribers’ expectations, the delivery rates will drop. This is why it’s so important to maintain profound contact with your audience. 

Moreover, pay attention to formatting since people appreciate nice layouts. At the same time, it’s essential that you check all structural semantics for HTML text. As said earlier, its elements might cause unnecessary problems if they are too heavy or don’t meet other requirements of ESPs. This is why it’s so important to test your emails before sending them. Folderly can help you do it with little to no effort and fix any issues that you might reveal.

8. Avoid purchasing email data lists

Purchasing emails aren’t recommended as they usually turn out to be a set of random addresses. Even if you buy a list of “warm” leads that might be potentially interested in your services, there’s no guarantee that your emails won’t end up in a spam folder. 

The fact is, today’s email service providers (ESPs) use advanced algorithms to prohibit such activities:

  1. They will blacklist unsolicited emails without regard to their relevance.
  2. Your recipients will be likely to get an extra opt-in to make sure they’ve subscribed to your messages.
  3. Even if your messages make it to their inbox, there’s a risk of poor performance.


Your purchased contacts might have already received thousands of similar offers before!

Thus, it is better to invest your time in lead nurturing, even though it will take longer. And if you feel too impatient to get a list of great prospects, resort to Belkins. Having an impeccable reputation, this company is well-known for white-label lead generation. Belkins experts will quickly find the most relevant audience in your field to bring you the best results.

9. Tailor emails to your audience’s needs

Numerous companies lose customers because they don’t bother to offer them a choice. Likewise, some of your subscribers might want to get your emails but do it less often. Thus, give them several options to choose from. For instance, those can be receiving your messages every day, once a week, or on a monthly basis. Otherwise, people might get tired from unsolicited content and report spam or stop reading your newsletters altogether. 

There’s no doubt that your reputation grows when ISPs see that people are interested in your content and interact with it. Meet their expectations by segmenting your audience to enhance campaign engagement. This will considerably improve email deliverability. 

According to Folderly results, sending inbound marketing emails to the right audience typically results in: 

  • 98% delivery rate;
  • 20-40% open rates;
  • up to 5-10% click-through rate;
  • almost no messages are marked as “spam” or labeled as “promotions.”

And, sending relevant outbound emails can bring the following results: 

  • 99% delivery rates;
  • 50-80% open rates;
  • over 25% response rates;
  • almost no messages are marked as “spam.”

Indeed, your recipients want highly personalized emails meeting their needs. Here are a few categories that can help you segment your newsletters:

  • demographic data;
  • history of purchases;
  • location;
  • current status according to the sales funnel;
  • other intent data.

Although segmentation might consume more time and effort than creating a mass campaign, it will pay off in the long run, bringing you the most qualified leads. 

Furthermore, once you’ve segmented your audience, you should also enrich different kinds of data. For instance, it’s essential to enhance your new contacts’ information. More accurate data allows for more personalized communication that results in effective lead nurturing. Thus, don’t hesitate to perform the enrichment while your leads are willing to share the data. 

10. Validate your subscribers’ email addresses before sending any emails

Email validation is necessary for keeping your delivery rates high. It involves verifying your recipients’ addresses without sending test emails. 

Updating your list is essential for excellent campaign results. Did you know that a typical email database reduces by 22.5% every year since a part of subscribers are subject to attrition? Thus, you should maintain a clean list to avoid an increase in spam rates. 

Email validation usually comprises three steps: 

1. Checking whether the addresses meet the accepted formatting standards and if their domain and local parts contain any errors.

2. Checking whether the DNS works properly and the mail exchanger record can accept incoming messages. 

3. Receiving confirmation from the mailbox. 


Moreover, unengaged users who haven't opened your messages in 6 months or more should be subject to strict reviews. 

Here are the most popular reasons for being inactive that you should consider:

  • your messages get into spam;
  • the individual is no longer interested;
  • the recipient receives too many emails and lost yours.

As you can see, inactive recipients negatively impact your delivery rates, so it’s crucial to get rid of disinterested contacts as soon as possible. 

11. Let your subscribers unsubscribe

They say, if you love someone, set them free. Thus, allow your readers to unsubscribe easily from your newsletters and manage their preferences. Such an approach will improve the bond with your recipients. Moreover, it will help you get rid of irrelevant contacts who won’t convert into buyers. 

Thus, immediately provide your readers with an option to stop receiving your messages in one click. It is better to add the “unsubscribe” link in the header or at the bottom of your email template and make sure that it doesn’t require extra steps. Otherwise, the recipients may get too irritated and mark your email as unsolicited. 

There are two ways to add an unsubscribe link to your template:

  1. Insert a link to an unsubscribe form.
  2. Apply an unsubscribe URL.


You should write specific texts for the people who are about to unsubscribe. 

Please note that cold emails don’t usually include an “unsubscribe” button or link. Instead, they contain opt-ins, helping your subscribers make a quick decision on whether to keep your newsletter or quit. Adding such data below your signature will be more than enough to let your recipients know how to unsubscribe.

You can use this text as an example of an outbound email recipient:

Yours sincerely,

Ben Hopkins

If you don’t want to receive tips and tricks about progressive email deliverability techniques, let me know — hit “reply” and write “stop” in the subject line. Thanks! May your emails never get into spam again! 

As for your warm leads, provide them with a personalized message so that they think twice before they hit “unsubscribe.”

Here’s an example of an unsubscribe text for inbound marketing emails.


Unsubscribe successful! Please take a moment to share why you decided to leave:

  • I receive too many emails from your company.
  • I signed up due to a promotion, so I’m no longer interested in getting your newsletters.
  • The content is irrelevant and doesn’t match my needs.
  • I can’t remember subscribing to your newsletters.
  • I have difficulty getting emails from your company.
  • Other (please explain below.)

As you can see, it is better to find out the reason why your subscribers decided to leave. Such an approach will help you enhance your content and communication strategy. Moreover, you can offer users to adjust their email frequency instead of quitting altogether. Furthermore, you can add your social media buttons at the bottom of the “unsubscribe” page to give users a chance to use an alternative communication method. You should also make sure that the unsubscribe link leads to the sending domain, for instance,

12. Monitor sender reputation and sender score

As mentioned earlier, this kind of reputation is of the utmost importance for your delivery rates. Thus, do your best to monitor it on a regular basis. Apart from the solutions provided above, you can use modern tools, such as Folderly, to track your score and analyze any issues you may come across, such as:

  • irrelevant content;
  • inappropriate target audience;
  • an unacceptably high number of messages;
  • technical errors.

You will considerably improve delivery rates if you regularly perform such monitoring.

Additionally, make sure that your email server hasn't been involved in sending spam. If ESPs suspect it, they might start redirecting your messages to a black hole, and they won’t end up in your recipients’ inboxes again. This means that ESPs have blacklisted the domain or the IP (and they don’t usually send a notification!) Such actions can significantly damage the results of a campaign. 

Take the following steps to find out if your IP address is safe and sound:

  1. Enter your IP or domain name on an open blacklist website (e.g., net.)
  2. Apply a free blacklist checker.
  3. Gain insights from your metrics and pay particular attention to delivery and open rates.
  4. Send test emails to analyze the way they get delivered.
  5. Use an email monitor system to track blacklists automatically.


These steps won’t require extra effort, but they will significantly enhance deliverability.

13. Use a separate subdomain for email activity

Before proceeding to practical advice, we’d like to explain the difference between a subdomain and a mirror domain.  

A subdomain is an additional part of your domain that “expands” it by using a separate prefix before the original domain name. For instance, is a subdomain of Using it allows for introducing more innovations since the changes you make on a subdomain don’t impact your main website. 

A mirror domain has the same name as the original website, but it uses another server for hosting. Thus, it may possess a different URL, but it contains the same content as your original website. For instance, is a mirror domain of  

Unlike the outbound campaigns that typically involve mirror domains, the inbound ones work best with subdomains. You can significantly enhance your online reputation if you create separate subdomains for different marketing campaigns. How does it work, exactly?

A subdomain can be of great help if the number of email addresses exceeds the capacity of the main one. Come up with an email address based on the subdomain you’ve created. For instance, it can be or

First, it will be easier to monitor your IP reputation and come to terms with filters if any problems arise. 

Second, your readers will start trusting the subdomain over time. 

Third, you’ll be able to use different subdomains for achieving different goals. 

In fact, transactional and marketing emails should be sent from different addresses. Otherwise, one of your teams will inevitably see a decrease in engagement levels. 

Finally, using several subdomains means that you don’t put all eggs in one basket. If one of them gets blacklisted by ISPs, you can always rely on the second one. 

14. Use a recognizable sender name 

Although this may sound obvious, your sender name is supposed to represent your brand. Your recipients should quickly recognize it among dozens or even hundreds of other daily emails in their inbox. Additionally, you can end your messages with a “handwritten” signature to increase the level of personalization.  

15. Warm up your email address, IP, and domain

You should not only keep proper IP allocation but also warm it up. Do it before you start sending new messages. Warming up your dedicated IP is key to building trust with Internet Service Providers (ISPs). You should convince them that your content isn’t of spammy nature and comes from a reliable source. Furthermore, you should do the same with your domain and email address to enhance deliverability. 

Investing your time in learning how to warm up emails is worthy every minute. After all, simply collecting a list of contacts and sending emails to them isn’t enough to make the most of your campaigns. You should apply analytical tools to keep deliverability at a high level. If you ignore the engagement signals, you might put your business at risk of wasting too many valuable resources. At the same time, segmented campaigns provide a 760% increase in the profit gained from email campaigns. Therefore, investing time and money in preparing your IP, domain, and email for sending is totally worth the effort. 

16. Send on a regular basis

Apart from complex technical issues, deliverability may suffer due to a lack of action. Sending emails without any plan is no better than spamming too often. Thus, stick to a precise schedule; otherwise, recipients won’t take your offers seriously. 

Moreover, you should not only send emails regularly but do it in progressive stages. This means that you shouldn’t start with large volumes. It’s better to come up with logical email sequences instead, following up with the content in which your customers expressed the most interest. 

17. Use all-in-one email deliverability monitoring platform

There is no doubt that the tips mentioned above will enhance your delivery rates. However, it is challenging to apply all of them as a series of complex measures. Thus, we offer you a comprehensive solution — Folderly mail checker. It will analyze and fix any issues to skyrocket your delivery rates so that you can focus on other important tasks. 

Our revolutionary email tool will provide you with:

  • Anti-spam program;
  • Comprehensive domain reputation analysis;
  • Maintenance of your sender score;
  • in-depth email deliverability analysis;

With Folderly, your emails will go straight to the inbox of your prospects. Folderly will analyze your email infrastructure and draw your attention to the issues that negatively affect deliverability.

Our all-in-one platform will make your life so much easier, helping your business grow quicker. 


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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