The best email deliverability practices to avoid the spam folder


Kristina Lauren

You know you put a lot of effort into your email marketing program from idea conception to design to code to the actual send of an email campaign. From there, you’d expect the process to go smoothly and as intended—your email lands in your subscribers’ inboxes, they interact with the email, and you hopefully get conversions or at least learn more about your audience. 

But none of this is possible if your emails don’t actually make it into your customers’ inboxes.

The factors that go into ensuring successful deliverability aren’t always so apparent. With ESPs on the constant hunt for malicious spammers and phishers, it’s easy for well-meaning email marketers to make mistakes that can over time impact the success of an email marketing program.

That’s why in this blog post we’re going to tackle the main factors that affect deliverability as well as the best practices to implement to keep your email reputation high.

4 Factors that Affect Email Deliverability 

1. Sender Score

Your sender score is essentially like a credit score for email. It's a numerical value between 0 and 100, and the higher your sender score, the more likely your emails are to be delivered to the inbox. Your score is typically based on factors like subscription rates, spam complaints, and bounce rates. Having a high sender score means that your email will be more likely to bypass spam filters and make it to the inbox, while a low score means the opposite.

2. Content of the Email

Unfortunately, email spammers can be quite relentless, so most email servers have protocols set to identify spammy content. Algorithms are developed to scan emails and look for suspicious keywords, attachments links, promotional phases, or code.

For example, if there are any links in your email that direct your audience to poor quality websites or if URL shorteners are used, ESPs identify these as red flags. If this happens often enough, your deliverability will be negatively affected over time.

3. Bounces Rates

High bounce rates are often a sign that your email isn't landing in the right inboxes. And as you can probably guess, high bounce rates can have a serious impact on your email deliverability. It’s important, however, to note the difference between soft and hard bounces. 

A soft bounce is usually the cause of a temporary error with your recipient’s ESP, such as a full inbox or a down server—both of which would be issues on your recipient’s end. A hard bounce, on the other hand, signals a more serious issue, like an invalid email address or a nonexistent domain name, which you would need to address on your side.

4. Volume

While maintaining consistent and frequent communication with your subscribers is a good practice, the more emails you send at once, the greater the likelihood that some will end up in spam folders. This is because email providers see high volumes of emails from a single sender as a sign of spamming behavior, and may automatically filter some out.

Avoiding sending multiple emails in quick succession by spacing out your email campaigns can help you not only keep your sender score in check, but your subscribers will also likely be more receptive. 

6 Best Practices To Improve Deliverability Rate 

1. Use Double Opt-in

Using a double opt-in serves as a method to get additional confirmation from subscribers who want to join your email list while weeding out any low quality subscribers who could clog up your email list with poor engagement. Although this method means that your email list may not grow as fast because of the extra step, in the long-term, you will still reap the benefits of better deliverability.

By using double opt-in, you would also be protected against spam complaints and be in compliance with the CAN-SPAM act. 

2. Give An Easy Opt-Out Option

Email marketers are required to give subscribers an option to opt-out at any given time, according to the CAN-SPAM Act. You want to make the process as easy as possible for your subscribers—if they can’t find the option to opt-out or if it’s simply too complicated, they might just take the easy route and mark your email as spam.

The best thing to do would be to include an opt-out or “unsubscribe” button in all your emails so your subscriber can easily find their way out. You can also ask your former subscriber why they chose to leave your list, which can be excellent feedback as you continue to communicate with your existing and new customers. 

3. Start Slow With An Engaging Audience

To stop spam emails from landing in their user's mailbox, email service providers strictly monitor new email IP addresses. When you are just starting your email marketing campaigns, it’s best that you take things slow in the beginning.

Start by only sending emails to a selective audience and build up your engagement gradually. This will signal to ESPs that your IP is credible and trustworthy. From there, you can gradually increase your volume if necessary—just keep in mind that the quality and value of your emails should always outweigh quantity. 

4. Use only One Sender Name   

To gain your audience’s trust, they need to recognize you when you communicate with them. The best way to do this is to create a sender name that consists of both your first name and your company name. If your audience keeps getting all the emails from one sender name, it becomes easier for them to identify you.

On the contrary, It can be more practical for companies to have more than one sender, especially if your customer will be communicating with multiple departments or divisions throughout their buying journey. If that’s the case, another solution is to use more general, but professional group names, such as “Service Department” or “[Company] Sales Team”.

5. Use Links Instead of Attachments

Attachments are treated with suspicion by email providers since many hackers use them to get access to the devices of recipients. To improve your email deliverability avoid sending attachments completely. 

To share an ebook, case study, or other documents, it’s best to upload them to your website and include a link to that page within your email body. If you need to draw more attention to the link, you can also make it into a CTA button.

6. Send Personalized Emails

There is no shortage of content on the internet, so as a marketer, you want to be the one to turn down the noise for your audience and give them information that they truly value. A good way to make sure that you provide the right content to the right person is by segmenting your email list.

Segmenting your list allows you to better personalize your subscribers’ email experience which in turn increases the chances of getting your emails opened and improves the engagement with your overall content. 

Tools for Email Deliverability

1. ZeroBounce

ZeroBounce allows you to validate over a million email addresses, score these addresses, test your emails, and keep an eye out for any blacklists your domain might be on.

2. GlockApps 

With GlockApps, you can see exactly where your emails are landing, monitor your domain, and identify potentially spammy content or code before hitting send.

3. SendCheckit

This simple but effective tool can be used to check how good your subject lines are. Once you enter your subject line, the tool gives you a full report of what you did well and what can be improved.


Improving email deliverability is a process that takes time, patience, and effort, but it's well-worth it in the end if it means continuing to grow your list and increasing your engagement.

However, email deliverability issues can vary from sender to sender so if you still need some guidance with understanding how to boost your email reputation, our email experts at Scalero are here to help. Contact us here to get started!

Join our mailing list

Get your fix of marketing, design and automation tips, all written by industry experts. +1 510-394-2442San Francisco, CaliforniaMexico City, MexicoCopenhagen, Denmark