Deliverability in Email Marketing

Deliverability is a crucial term in email marketing, as it determines how many of your bulk emails actually reach recipients’ inboxes.

In other words, good deliverability ensures that your subscribers receive your messages and that your email marketing campaign doesn’t get lost in the shuffle because of spam or email filters.

Next, we’ll explain what deliverability is , how this concept works in bulk email sending, and how to improve it to boost the success of your email marketing campaigns.

What is email marketing deliverability?

Deliverability in email marketing refers to the ability of your emails to reach your subscribers’ inboxes, rather than ending up in the spam folder or other secondary tabs.

This metric measures what percentage of emails sent are actually delivered successfully to the recipients.

Simply put, if you send 100 emails and 90 reach the users’ main inbox, we could say you have a 90% deliverability rate.

The standard formula to calculate this percentage is:

deliverability rate = (emails delivered / emails sent) × 100

It is important not to confuse deliverability withthe“ n open rate”or the“click-through rate.”

Deliverability only measures whether an email is delivered ( i.e., whether the message reaches the inbox), without taking into account whether the user then opens it or interacts with it.

Now that we have clarified what deliverability means, let’s see why achieving a high rate for your email campaigns is so important.

Why is deliverability important?

Deliverability is vital because an email marketing campaign is useless if your emails don’t reach the recipients.

No matter how well-designed your newsletters are or how attractive your offers are, if they end up in the spam folder or aren’t delivered, your efforts won’t yield results.

This translates into lost sales opportunities and a wasted investment of time and resources.

In addition, poor deliverability can damage your brand’s reputation.

When subscribers provide their email address, they are placing their trust in your company.

If your emails fail to reach their inbox, that trust is compromised.

As a result, poor deliverability affects your business’s credibility and even your revenue, since fewer emails being opened means fewer potential conversions.

In short, ensuring good deliverability is essential to the success of any email marketing strategy: it guarantees that the message reaches its audience and maximizes the return on investment of your campaigns.

How does email deliverability work?

Email deliverability works by taking multiple technical and behavioral factors into account.

Several factors come into play with every email campaign (your sender domain, the email platform, email providers’ filters, and the recipients themselves) that will determine whether a message reaches the inbox or is filtered out.

Essentially, deliverability is the result of a combination of key elements, including:

3 Sender reputation:

The reputation of your sending domain and IP heavily influences deliverability.

If you’ve consistently sent high-quality emails with low spam rates, email providers (such as Gmail, Outlook, Yahoo, etc.) will trust your messages more.

On the other hand, if your domain or IP address is blacklisted or has generated a lot of spam complaints, your emails will have trouble reaching their destination.

· Quality of the contact list:

The hygiene of your database is another crucial factor.

Sending emails to invalid, outdated, or inactive addresses harms deliverability because it increases the bounce rate and may signal to providers that you’re not managing your email campaigns properly.

Maintaining a clean list (without non-existent or inactive contacts) ensures your messages are only sent to real and interested recipients.

· Subscriber interaction:

The behavior of your readers also affects deliverability.

If users regularly open, read, and click on your emails, email providers will interpret your messages as relevant and desired, improving your chances of reaching the primary inbox.

On the other hand, if many subscribers mark your emails as spam, delete them without reading them, or never interact with them, spam filters will interpret your content as unwanted and may move it out of the inbox in future mailings.

· Email content and anti-spam filters:

What and how you communicate in your emails influences their delivery.

An overloaded design, containing only images or using excessive spam trigger words (like “free”, “offer”, “urgent”) can trigger anti-spam filters.

Similarly, poor HTML formatting or suspicious links are a red flag for filters.

Email services analyze elements such as the subject line, message body, and formatting for signs of spam or phishing.

If the content seems suspicious or inappropriate, the email will likely end up in the spam folder.

· Authentication and technical setup:

Technical aspects such as configuring SPF, DKIM, and DMARC —email authentication protocols—have a direct impact on deliverability.

These settings tell the recipient’s provider that your emails are actually coming from you (from your legitimate domain) and not from an imposter.

For example, a correctly configured SPF indicates which servers are authorized to send on behalf of your domain, and DKIM adds a digital signature to your messages.

If you don’t have these measures in place, many servers might reject your emails or mark them as suspicious.

Having an email marketing platform that properly manages these authentications significantly improves your delivery rates.

In summary, deliverability works as a delicate balance between reputation, contact list quality, the content you send, and the technology backing your emails.

Understanding these factors will help you identify what might be failing if your emails aren’t arriving and, above all, how to fix it.

How to improve deliverability in your email marketing campaigns?

Achieving good deliverability is not a matter of luck, but of consistently applying a series of best practices.

If you are wondering how you can increase that inbox delivery rate, below we review several key tips.

By following these recommendations, your bulk email campaigns will be much more likely to end up in your subscribers’ inboxes:

· Use a reliable and high-quality email marketing platform

The first step to improving your deliverability is ensuring you send your emails through a reliable email marketing tool.

Professional platforms (such as Mailrelay, for example) have optimized infrastructure, servers with a good reputation, and strict anti-spam policies.

This means that by using a reputable service, your messages start with an advantage in being accepted by email providers.

Additionally, these platforms usually handle complex technical aspects – such as SPF/DKIM authentication or blacklist monitoring – so you don’t have to worry about them.

In short, rely on a good bulk email service that ensures the deliverability of your campaigns from a technical standpoint.

· Implement double opt-in on your subscription forms

An effective way to protect your deliverability is to build a list of contacts who are genuinely interested in your content.

To achieve this, use double opt-in for subscriptions: this method requires the user to confirm their email by clicking a confirmation link sent to their inbox after registering.

Why does this help?

Because it ensures that every email address in your database belongs to an active person willing to receive your messages.

With double opt-in, you avoid fake or incorrect contacts and guarantee higher-quality subscribers, reducing future spam complaints and improving the performance of your campaigns.

· Don’t buy email lists or send emails without permission

It may sound tempting to try to quickly grow your list by purchasing a database or adding contacts who haven’t given their consent, but this is a bad practice that seriously harms deliverability.

Contacts who haven’t subscribed to your emails are very likely to ignore them, delete them, or mark them as spam.

The latter, in particular, is devastating to your reputation as a sender.

Furthermore, in many countries, sending unsolicited emails violates data protection regulations.

Therefore, build your list organically: gather subscribers through forms on your website, events, social media, or other channels where they voluntarily express their interest.

Quality is better than quantity when it comes to email marketing.

· Keep your subscriber list clean and updated

Email list hygiene deserves constant attention.

Over time, it is normal for certain contacts to stop interacting or for some email addresses to cease to exist (due to job changes, new providers, etc.).

That is why it is important to regularly clean up your database.

Remove or try to reactivate subscribers who have been inactive for a long time, and be sure to remove email addresses that generate hard bounces because they no longer exist.

Maintaining a clean list reduces the proportion of emails that never arrive (due to full or non-existent inboxes) and shows ISPs that your sending practices are responsible.

As a result, your deliverability will improve because you’ll be sending emails to an audience that is truly active and interested.

· Take care of your email content and formatting

The content you send is your cover letter to both spam filters and your subscribers.

To optimize deliverability, send high-quality, relevant content to your audience.

Avoid overusing words considered spam or flashy symbols in the subject line (like ALL CAPS or exclamation marks such as “BUY NOW!!”), as they can trigger alerts.

Similarly, it balances text and images—an email consisting of a single large image with very little text may raise suspicion with filters.

Ensure your message is well-formatted, with clean HTML if you use it, and include descriptive alt text for your images.

A clean, professional, and useful email is more likely to pass anti-spam filters and also capture the positive attention of your subscribers (which, in turn, improves future deliverability).

· Segment your campaigns and personalize the message

Not all your subscribers are the same, so sending everyone the same message can result in a lack of interest from many.

By segmenting your list into more specific groups (for example, by interests, geographic location, stage in the buying cycle, etc.), you can personalize the content and send truly relevant information to each segment.

Why does this improve deliverability?

Because recipients get emails they are interested in, making it more likely they will open and interact with them.

Higher engagement (opens, clicks, replies) signals to Gmail, Yahoo!, and other providers that your emails are well-received, reinforcing your reputation as a legitimate sender.

As a result, segmentation and personalization are a winning strategy: they improve the user experience and boost your delivery metrics.

· Send with the right frequency and consistency

Consistency in your sending frequency also plays a role in deliverability.

Try not to go from 0 to 100 abruptly; that is, avoid sending very few emails for weeks and suddenly sending a massive volume all at once, as those unusual spikes can trigger spam alerts.

It is advisable to maintain a regular sending frequency (for instance, a weekly or monthly newsletter, depending on your strategy) so that both your subscribers and email servers “expect” your messages.

If you need to increase your sending volume (for example, during a special promotion), do so gradually or in stages.

This process, known as “warming up” (IP or domain warming up), helps email providers view your increase in email volume as normal.

In short, send emails on a regular and consistent basis, because extreme irregularity can harm your reputation and, as a result, your deliverability.

· Configure authentication: SPF, DKIM (and DMARC)

Lastly, don’t neglect the technical aspects backing your sends.

Configuring SPF and DKIM records on your domain is essential to improve the deliverability of your emails.

These protocols serve to validate that you are who you claim to be when sending an email: SPF specifies which servers are authorized to send emails from your domain, while DKIM adds a digital signature to each message to confirm it hasn’t been altered and comes from a reliable source.

Implementing DMARC as well can give you an extra layer of protection, instructing receivers on what to do if a message fails SPF/DKIM checks (for example, rejecting it or sending it to spam).

By having these authentications correctly configured, your emails will build more trust in the eyes of Gmail, Outlook, and others.

Many email marketing services guide you through this process.

Taking the time to activate SPF, DKIM, and DMARC directly results in a higher delivery rate.

What is the best email marketing tool to improve deliverability?

Choosing the right platform can make a huge difference in the deliverability of your campaigns.

The best email marketing tool will be the one that offers a solid infrastructure, strict anti-spam policies, and support to implement sending best practices.

Mailrelay, for example, stands out as a platform designed to maximize deliverability: it offers high-reputation servers, the ability to easily configure SPF/DKIM, and an expert support team that is there to assist you at all times.

In addition, Mailrelay offers you the most generous free plan on the market (up to 80,000 emails per month to 20,000 subscribers) and live technical support for all accounts, including the free one.

These advantages allow you to improve your deliverability with zero initial investment, as you can send mass campaigns, monitor your results, and clean your lists with professional help.

Ultimately, if you want to ensure that your emails reach the inbox, it’s crucial to rely on a reliable email marketing tool like Mailrelay, which combines excellent technical features with expert support.

This way, you can focus on creating great content while the platform ensures your messages reach your customers!