Proven Tips & Best Practices to Improve Email Deliverability in 2024

Proven Tips & Best Practices to Improve Email Deliverability in 2024

Sofi Kompaniiets
Mar 21, 2024
Reading duration
25 min

Struggling to improve email deliverability despite implementing "clean list" and "spam-free subject line" best practices? You're not alone. Many resources focus on these fundamental elements, but achieving optimal deliverability requires a more comprehensive strategy.

This article delves into both basic and the lesser-known, yet highly impactful, email deliverability tactics. Having dispatched 2+ million emails in the last three years, assisting in the setup of outbound lead generation for our parent company's Belkins clientele, and after enhancing domain reputation for hundreds of Folderly clients, we understand all the nuances of email deliverability. 

For instance, did you know that even using open rate tracking for your emails or bold font in the copy can become the reason for spam? ๐Ÿค” This is the real scenario our customer experienced.

So, let's get right into the uncommon and less-known tips and practices (tested and proven by Folderly deliverability experts) to improve email deliverability.  

The Article Walkthrough:
โžก๏ธ What Affects Email Deliverability: 4 Pillars
โ€‹โ€‹โžก๏ธ How to Know Your Deliverability Rate & Spam Reasons
โžก๏ธ Email Deliverability Best Practices for Sender Reputation
โžก๏ธ Email Deliverability Best Practices for Recipient Database
โžก๏ธ Email Deliverability Best Practices for Content
โžก๏ธ Email Deliverability Best Practices for Email Tools
โžก๏ธ Not Advanced Yet Classy Tips and Practices Recap ๐Ÿ’ก

4 Pillars of Email Deliverability (What Affects Email Deliverability)

You can’t address only one area and hope that your email sender reputation is safe and sound.

Making sure all components that affect email deliverability are well set is the key to ensuring 96% and above inbox placement.

So, what exactly impacts your email deliverability rate? A comprehensive approach to email deliverability (which we’re ambassadors of at Folderly) includes paying attention to all four pillars of email deliverability: sender reputation, recipient database, content, and proper outreach tool setup.

Components of Email Deliverability

The sum of all these pillars determines your email deliverability rate.

In other words, 100% email deliverability = excellent sender reputation + impeccable recipient database + spam-free content + correct tools setup

We use this formula to set up email deliverability for ourselves and implement it for our clients. 

Before You Start: Learn Your Deliverability Rate & Exact Spam Reasons

How do you know why major ESPs flagged your email as spam? What exactly triggered email spam filters? 

Most of our clients come with the same challenge—they don't change anything in their email outreach behavior, yet emails fail to reach users' inboxes without a reason. They have a hard time knowing where to begin when trying to identify the causes of spam.  

No more guesswork with the Folderly Score and Spam Triggers features.

Once you've linked your email to Folderly, your Folderly Score is constantly monitored and evaluated.

Folderly Score Dashboard Demo

Folderly score is a unique metric that takes into account the inbox rate of a user's mailbox, the presence or absence of spam triggers, and the adoption of best practices for email deliverability. 

In addition, it shows the percentage of your messages that end up in your Inbox, spam, and other (promotional) folders.

Besides, you can also gain insight into the specific spam triggers that cause your emails to be classified as spam. So, you don’t need to guess anymore and know where to start.

Save time and effort with a comprehensive email domain health check by letting Folderly do what it does best.

Email Deliverability Best Practices for Sender Reputation 

Your reputation as a sender is defined by the combination of three levels: IP Reputation, domain reputation, and mailbox health. Let’s call it a 3-level reputation cycle:

Components of Sender Reputation

All these levels are interconnected, and the tips and practices we’ll discuss usually affect all of them.

Set up and regularly update your DNS settings

DNS stands for Domain Name System, which connects domain names with their respective IP addresses. DNS settings can be defined as the instructions that help email systems find and deliver your emails correctly. 

It's like providing a map for your email to reach its destination without being lost in spam folders or bounced back.

The basic records you need to add and monitor either manually or with email deliverability tools within your DNS are SPF, DMARC, and DKIM + BIMI (*for big companies)

Setting your SPF 

SPF (Sender Policy Framework) TXT record, is a list of trusted email servers that are allowed to send emails on your domain's behalf. It means you need to update it every time you remove or add a tool that sends emails from your domain. Otherwise, the email that hasn’t been added will be defined as untrusted, and you’ll encounter problems with deliverability. And vice versa, try to keep your SPF Record clean by removing any tools or applications you are no longer using from your SPF record.

An example of a properly set-up SPF:

v=spf1 a ip4: ~ all

 ๐Ÿ‘‰ Before creating and adding a new SPF, you need to delete a previous one, since it’s crucial that your domain doesn’t have multiple SPF records. You can read more about how to set up SPF record correctly in our detailed guide.

Setting your DMARC

DMARC, or “Domain-based Message Authentication, Reporting & Conformance,” is another type of email authentication. It is an authentication protocol that builds on the SPF & enables domain owners to know how email should be handled when it fails SPF authentication.

An example of a properly set up DMARC:

v=DMARC1; p=reject;;; fo=1; sp=quarantine;

๐Ÿ‘‰ The process of updating your DMARC record may vary based on the DNS/web hosting provider you have. Check the compilation of the detailed guides for your hosting provider. 

Setting your DKIM

DKIM stands for DomainKeys Identified Mail and is used for the authentication of an email that’s being sent. It keeps the public key the receiving mail server will use to verify a message's signature.

 ๐Ÿ‘‰ Setting up and adding your DKIM instructions would also depend on your specific provider. You can check out a list of links to the documentation of popular providers in this guide.

Setting your BIMI

BIMI stands for Brand Indicators for Message Identification. It’s like a tick for a Twitter account. This record is something that is often missing in other guides. This indicator allows your recipients to see your logo next to your incoming email in their inbox.

BIMI works together with DMARC, DKIM, and SPF so the email service providers of your recipients will identify you correctly and let your messages be displayed in the inbox.

  ๐Ÿ‘‰ You can find a detailed guide on how to get a verified mark certificate and how to implement BIMI, step by step.

Increase sending limits gradually

Remember the inspiring talks about the power of small steps?

The same philosophy should be applied to sending limits.

You can’t send 100 emails a day from a newly created inbox. If you're too active and reaching out to too many prospects, spam traps might get suspicious because your domain address doesn't have a solid reputation yet.

So, before you start your campaigns, you have to convince the systems that you're a trusted sender and that your emails are worth giving the green light. One by one.

Everything starts with a preparation stage. Here's what we recommend:

8-12 weeks warmup:

  • Starting with sending between 20 and 30 emails per day

  • Increasing the number of sent emails by 10 daily  (if your spam rate is not changing)

  • After your domain is warmed up, still limit yourself to 200 emails a day

The exact term will depend on the rules of your provider, but on average, it takes 2-3 months. So you'll need some patience. 

Send no more than 200 emails from one mailbox (for cold outreach)

We never recommend sending more than 200 cold emails from one mailbox, even if the limit set by your provider is higher.

But what to do if your KPIs require sending 600 emails a day? Well, then, the solution is creating two more mailboxes, so you can send 200 emails from each and reach the KPI.

Also, remember that email providers have custom daily sending limits for the number of all emails sent. Never exceed them if you don’t want to kill your sender's reputation.

Sending limits for popular email clients: 

  • Gmail Free Account: 500 emails in a 24-hour period,  and a maximum of 100 addresses per email. 

  • Paid Google Workspace Account: a maximum of 2,000 emails in a 24-hour period.

  • Outlook Free Account: up to 300 emails per day

  • Paid Microsoft 365 accounts: 10,000 emails per day

Yahoo! Mail Plus:  maximum of 500 emails a day (to a maximum of 100 recipients)

Ensure there is a smart delay between cold emails

It’s important to show your chosen email client service that you are a real person sending meaningful emails, rather than a spammy bot. And this is where a smart delay comes into play.

The best delay we recommend to our clients (and use at Folderly as well) is 180–200 seconds. 

It means that when launching your email outreach, you should either set an automated delay between emails of 180–200 seconds or adhere to it yourself if you are sending it manually.

Use separate domain for warm and cold outreach

If you use your corporate domain for warm outreach, it will be affected by low email engagement rates and will lead to lower sender reputation.

 2 ways to organize your outreach infrastructure: 

RISKY OPTION:  Using your current domain or subdomain for both cold and warm outreach.


โ— Also, based on our experience, we recommend buying several reserve domains if your budget allows it. It will help you to get ready for unexpected situations when something goes wrong with your main domain and ensure that, in such cases, your outreach will continue. 

Choose email outreach tools that have their own IP addresses (for warm outreach)

Why it matters? Considering that in most cases, cold outreach is done from shared IP addresses, the reputation of which is difficult to control, tools with their own dedicated IP address assign their IP to your domain, so you are safe and sound. 

  ๐Ÿ‘‰Based on our internal research working with Folderly clients, HubSpot has the strongest IP reputation, while Klaviyo is associated with the poorest one.

Double check before buying a dedicated IP (for warm outreach)

Let’s start with a small theory. An IP address can be either shared or dedicated. Usually, a number of users, websites, or organizations share the same IP. So, if shared IP is your case, your emails are gathered and sent through the same IP as the emails of people sharing your IP.

Unlike shared IPs, a dedicated IP server is associated with a single user, website, or corporation. Senders interested in high sending volumes use this option, which is safer but more difficult and resource-intensive to maintain. We recommend using dedicated IP only if you send at least 500K+ millions of emails a month.

Shared IP vs Dedicated IP

And if your business is shifting to a dedicated IP, you should never rush into buying an address. Often sellers offer IP addresses with ruined reputations. So, you need to carefully check the IP address and its past history before making a buying decision.

You can read more about the difference between shared IP vs dedicated IP in our guide.

Select a trustworthy domain name and zone  

Choosing the right name for your domain requires avoiding certain elements that may trigger spam filters or create a negative perception among recipients. You can read a detailed guide in our help center, but here’s a quick summary of what you should do, and what you should avoid: 

Best Practices To Follow

Things To Avoid

Using brand name or relevant keywords

Ensure that your brand name or relevant keywords related to your business or industry are part of the domain name.

For instance:

Special characters:

Avoid using hyphens and numbers unless necessary. 

Using positive connotations

Choose words that have positive connotations or reflect your brand's values and image.

Spammy words

Avoid words that are often associated with spam, such as "free", "prize", "bonus", "buy", "promo", "sale", "opportunity", "info", "mail" etc.

Choosing the top-level domains

.com, .io, .co, .net, .org 






Complex spellings

Avoid difficult words to spell or pronounce to ensure clarity and communication.

Long strings of words

Avoid concatenating too many words together (e.g.,

Generic names

Too generic names might lack uniqueness and may not stand out.

TLDs Associated with spam

Be cautious with certain Top-Level Domains (TLDs) often associated with spam or malicious websites (e.g., .xyz, .info).

Similarity with other brands

Avoid names too similar to existing brands or domains to prevent confusion and potential legal issues.


๐Ÿ‘‰ Extra tip: If you are planning to target a specific audience (for instance, your clients will be UK-based), then, it makes sense to choose a local zone for your domain address (e.g. .uk).

How Can Folderly Help with Sender’s Reputation? ๐Ÿค”

With Folderly's intuitive deliverability placement dashboard, you get access to real-time sender reputation monitoring, with Folderly score, and email deliverability insights. It helps to determine trends, make better-informed decisions regarding mailbox and email campaigns, and address issues before they kill your sender's reputation.

After launching Folderly (even with a 7-day free trial), you also get your DNS scanned, reviewed, and checked with spam trigger detection feature. If everything is okay, all your DNS settings will be marked as “pass.” However, if not, Folderly will highlight that it needs to be fixed and will suggest the best practices to do it.

Also, with  professional email deliverability consulting, you get a complete analysis of your domain DNS settings. Folderly experts configure all the necessary sender authentication DNS settings for your domain, so your domain is fully and properly authenticated as a trusted sender identity.

Besides, you can always use our free tools—SPF Generator and DMARC Generator for manual setup.

Email Deliverability Best Practices for Recipient Database

To keep your email deliverability in tip-top shape, you need a squeaky-clean prospect list. You should be confident that you made the right decision and that a sent email will be relevant to the receiver (and that prospect data is correct, so the email will not bounced).

So, let’s look at the tips that go beyond “cleaning your contact list regularly”:

Don’t trust websites selling leads

We cannot stress enough the importance of not putting your faith in websites that sell leads. Buying leads is not only against email compliance, but it also rarely produces real value for businesses, which is why we at Folderly strongly discourage it. If you target people who are not your target audience, in the best scenarios, your emails will have low engagement rates, which negatively affects your email deliverability rate.

But we realize there are times when you might be in need of such a solution. Extreme caution is required in such situations. In many cases, purchased contact lists are of questionable accuracy and relevance. Unsolicited email addresses are a common problem for our clients here at Folderly, as most people ignore it.

 ๐Ÿ‘‰ So, what we recommend is ALWAYS double-checking the email lists you buy, either with online tools like MailerCheck or (which is a more sustainable and trustworthy choice) manually by sending test emails to these addresses from your other email accounts.

Manually update your contact base once a month  

If you are launching warm outreach, it’s important to regularly update your contact base since emails have the tendency to become outdated. At Folderly, we take this matter seriously and employ a meticulous, 100% manual approach to ensure the accuracy of our contact base. While automated email checks can be convenient, they fall short of providing a reliable guarantee.

 ๐Ÿ‘‰ To be thorough and certain, we recommend the practice of sending test emails from a dummy or "fake" email address for verification purposes. This extra step can make all the difference in maintaining the integrity and effectiveness of your outreach efforts.

Avoid reaching more than three individuals within the same domain 

It's a best practice to avoid sending a high volume of emails to a single domain. Instead, we recommend a more targeted approach, ideally limiting your outreach to 2-3 individuals within a given company.

Following these secure rules helps maintain a positive sender reputation and increases the likelihood of your emails reaching the intended recipients without triggering spam filters or causing any delivery issues. Besides, often companies have secure protective measures, such as rejecting too many emails from a single sender.

Send cold emails only to business accounts, preferably using the same ESP

When sending emails from a Google email address (Gmail) to another Google email address (Gmail), or from one Outlook email address to another Outlook email address, you can generally expect smoother email delivery as these email services are well-integrated. 

However, it's important to note that when conducting cold outreach, it's advisable to avoid sending emails to free mailboxes. Instead, you should target only paid G-Suite business accounts (at Folderly, we use only such accounts for email deliverability fix). 

This helps improve your email deliverability and reduces the risk of your cold emails being marked as spam. So, by focusing your outreach efforts on more business-oriented email domains, you increase the likelihood of a positive response and avoid potential deliverability issues.

Email Deliverability Best Practices for Content

Now, let's go over how to make sure your prospects receive and open your emails, even with all the other emails they're getting.

We can't promise 100% open rates (unfortunately, nobody can). But at least you will significantly improve your chances by applying the following tips.

Use a free spam words checker

You’ve probably heard that some words within your email content can trigger spam. But we know that checking every email for them manually might be frustrating. That’s why we’ve created an online free spam word checker for ourselves and are happy to share it with you.

Detect and replace potentially problematic terms in a few clicks. It helps to maintain a good sender reputation and increase email deliverability by avoiding spam-inducing words.

Add lightweight attachments and visuals

โ—Important! The rule applies only to warm outreach. In cold outreach, we don’t recommend using any visuals or attachments at all. 

So, when sending warm emails, it's a good practice to include only lightweight attachments and visuals, and if they are necessary, make sure they are less than 100KB in size. Additionally, it's advisable to compress images using online compressing tools as much as possible without sacrificing quality.

This not only helps keep your email size manageable but also ensures that your emails load quickly and are less likely to be flagged as spam.

Keep emails less than 1000 symbols

*For cold outreach

Less is more.

When engaging in cold outreach, it's wise to keep your emails concise and to the point, ideally limiting them to less than 1000 characters or symbols. Shorter emails are more likely to capture the recipient's attention, and they are less likely to be perceived as spam.  

Add only internal, not shortened links (for warm outreach)

FYI: As for cold outreach, you should not use links in your emails at all.

When including links in your emails, it's advisable to use only internal links (the ones that direct recipients to your own website). Also, we recommend limiting the number of links to no more than 12 per email and avoiding using shortened URLs.

This approach not only ensures that all links lead to your website, enhancing your website's credibility and trustworthiness, but it also minimizes the risk of your emails being flagged as spam.

Test email deliverability with the same templates you use for outreach (including signature)

It’s recommended to perform email deliverability testing using the same templates you are going to send for real outreach. At Folderly, we use users’ custom templates (which can also be added in different languages) for testing and fixing email deliverability.

But the thing that is often forgotten is including email signatures in the templates you use for email warmup. It’s an inevitable part of your email that is also checked by content spam triggers.

So, make sure you keep that in mind when testing your email templates before sending them.

Update your email templates/sequences once every 2 weeks

Regularly updating your email templates and sequences is a crucial aspect of maintaining good email deliverability. Over time, email filters become more sophisticated, and what worked in the past may start triggering spam alerts. To stay ahead of these changes, it's recommended to refresh your email content every 2 weeks to a month. 

By doing so, you can adapt to evolving spam detection algorithms and improve the chances of your emails reaching their intended recipients rather than getting caught in spam filters.

Include opt-out link (for warm emails)

FYI: Using unsubscribe links is debatable in cold emails. So, instead, simply replace the unsubscribe link with the following element: "PS. Don't hesitate to let me know if you want our conversation to end here." Good news: it also counts according to the SPAM Act requirements.

Remember to provide recipients with the option to unsubscribe from your emails if they wish to do so.

  ๐Ÿ‘‰ Recommended tip: When selecting an outreach tool, it's essential to choose one that offers built-in unsubscribe functionality. Many email marketing and outreach platforms, including Gmail, have features that allow you to include an opt-out or unsubscribe link in your emails automatically. This ensures compliance with email marketing regulations and makes it easy for recipients to opt-out if they no longer wish to receive your emails.

Unsubscribe Link Demo

If you are using a tool that doesn't have this built-in feature, you can manually include an opt-out link in your email footer. Just ensure that the process for opting out is straightforward and user-friendly.

Use straightforward subject lines (no clickbait)

Using misleading subject lines (e.g., Your business is in danger)—a cheap trick from the past and movetón. Google emphasizes the importance of writing clear subjects for your emails. A well-crafted subject line not only grabs the recipient's attention but also conveys the purpose of the email upfront.

For sure, catchy subject lines spark curiosity. But when users open a cold email from you, they will feel cheated since it's unexpected. Think of a subject line as a key to unlocking a conversation with your prospects instead.

This rule is crucial for cold emails and recommended for warm emails.

Send emails in one primary language from each domain

Spammers often use a variety of languages to bypass filters, so major email providers like Gmail are on high alert when you start sending emails in another language.

Stick to one primary language for emails sent from each domain. This keeps things clear for recipients and avoids getting flagged as spam. Plus, it allows you to personalize your message and build trust with potential customers who share your language.

If you target a global audience, consider segmenting your email list by language and sending targeted campaigns in their preferred language. This shows extra effort and increases the chances of your message getting seen and understood.

How Can Folderly Help with Content? ๐Ÿค”

Folderly’ Template Editor analyzes your added email templates for spam triggers, detects and displays potential issues, and provides recommendations on how to fix them.

You can add your custom email templates, which will be used for email deliverability testing and email deliverability optimization. Besides, now you can add templates in different languages (the list of languages includes English, German, Spanish, French, Italian, Hindi, Arabic, Portuguese, and Turkish).

When you are satisfied with the final product, you can save all changes by clicking the Save template button. The editor will also display the number of characters and the estimated time it will take readers to go through their email.

 You can edit both plain text and HTML templates here.

Templates Editor Dashboard

Deliverability Best Practices for Email Tools

Tools can either kill or save your email deliverability, and the proper use of those, considering all the nuances, is a must-have for smooth email deliverability.

Don’t use cheap warmup solutions that offer a superficial approach

While a standard warmup solution only helps new mailboxes raise their sending limits, Folderly Spam Fix goes beyond and indeed fixes the spam problem using tech solutions that equal manual interaction with inboxes, moving every email that lands in promo or spam to the inbox and marking them as important. The solution we use imitates real people’s manual flow in every small detail, minding the gap between sending emails, using custom user’s templates, and sending only to paid G-Suite business accounts (FYI: You need at least $300 every month to upkeep the paid accounts, so a reliable email deliverability tool that follows the best practices just can’t cost $20).

Besides! To ensure your excellent sender reputation, you need to use a cyclic approach to email deliverability, not just one-time fix. It means users needs to keep Folderly running constantly to achieve good results.

Don’t use open rate tracking

So what’s the problem with open rate tracking? Well, it’s all about pixel tracking. To determine whether a user has viewed an email, a 1x1 pixel image that users can’t see is embedded in a webpage or email. When the email is opened, the image loads, sending a request to the server, which records it.

This invisible image can easily trigger spam filters. Therefore, this email performance tracking method should be used cautiously. Alternative metrics and strategies may be better for measuring email campaign success and impact, resulting in more safe decisions.

Use ONLY sales management platforms for your cold email outreach 

Email marketing platforms that help manage huge email volumes are a big NO-NO. You can use them only for bulk emails. Contrary to it, sales management platforms like Woodpecker, Outreach, and Reply are great tools for one-to-one communication, but in a smartly automated fashion.

Limit your email sequences to 6-8 steps 

When using tools for sequence automation, remember to limit your email sequences to 6-8 steps. While automation tools offer the convenience of managing sequences, it's important not to overdo it. Based on our experience, creating excessively long sequences with 15 or more steps often proves counterproductive and can lead to killing your sender's reputation.

Instead, we recommend focusing on concise and effective sequences with a maximum of 8 steps. This ensures that your message remains clear and relevant throughout the sequence. In fact, an even shorter sequence of 6 emails can be considered the golden middle, as it keeps the engagement focused and increases the chances of a positive response.

More Obvious Yet Important Tips

Now, back to the basics.

Let’s briefly recap some basic tips and practices everyone is talking about. They are also important components of email deliverability.

Double opt-in for warm outreach

This is not the case when the more prospects you contact, the better the results will be.

You want to connect with only potentially interested prospects who look like your ICP (and you mark them as such only after deep research). Therefore, always ensure a prospect is added to your email contact list only after double opt-in.

Delete emails with hard bounces immediately

Hard bounces typically result in a loss of sender reputation and increased email deliverability issues. Soft bounces occur as a result of temporary delivery failures caused by issues such as an overflowing mailbox or a service. Therefore, while monitoring your email deliverability, always make sure to immediately delete email addresses that bounced back. 

Avoid using bold and colored fonts

To improve email readability and professionalism, avoid using large, bold, or colored fonts. To ensure that your message is clear and easy to read, use a clean and simple text format.

Add the plain-text version of the letter if you send HTML emails

When sending HTML emails, always remember about text to image ratio. This ensures that recipients who prefer or can only receive plain-text emails will still be able to access and understand your message, improving your email's accessibility and reach.

For the best results, we recommend your emails have mostly text (around 65%) with a smaller amount of images (around 35%).


Unsubscribe inactive subscribers immediately

Inactive subscribers should be unsubscribed as soon as possible. By doing so, you can keep your email list in good shape, increase engagement rates, and ensure that your emails reach people who are genuinely interested in your content. This improves your email deliverability and allows for better targeting.

โ€‹โ€‹Perfect the opt-in process & let people rule over inbox

Make sure that people who sign up for your email list understand what they are signing up for. Be clear about how often they will receive emails, what type of content they can expect, and how easy it will be to unsubscribe if they no longer want to receive your emails. Offer people the chance to choose preferences in terms of content, time, and frequency. 

Bottom Line: Always Prioritize a Comprehensive Approach to Email Deliverability

The truth is that it's not as simple as the "to do" articles make it sound; fixing email deliverability with a few clicks on a mouse isn't possible. You need a holistic strategy for improving email deliverability if you want to see lasting results (and also you should constantly monitor changes to email compliance, such as Google sending requirements and others).

And high email deliverability and outreach ROI come from 100% control. Gain control of your sender's reputation and the placement of your emails with Folderly's AI-driven, all-encompassing deliverability optimization. 

Contact us at any time to speak with a knowledgeable member of the Folderly team and receive answers to any remaining questions.

Let’s bring your email deliverability to the next level together! ๐Ÿš€

Sofi Kompaniiets
Sofi Kompaniiets
Content Manager
Sofi is a Content Manager at Folderly. Harnessing the power of language, expertise in email deliverability, and digital storytelling, she crafts engaging user-first content that resonates with audiences and educates readers in simple and practical ways. Sofi works closely with email deliverability specialists to transform raw technical information into articles with great and applicable insights.

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