“How can I ensure my emails are being delivered?” One of the simplest questions in email marketing may also be the most complicated answer.

As an email marketer, you want to provide the best content to your subscribers. You want to see your subscribers sharing your content on social media and talking about your company and your offerings. You don’t just want to see your subscribers opening your emails; instead, you want to see them engage with your emails in more meaningful ways.

The goal here is not just about crafting beautiful, optimized emails. Instead, it is also about better positioning your email campaigns to reach the inbox of your subscribers, avoid any spam filters and then get opened and engage with your subscribers in meaningful ways. This is where the email deliverability factor comes in.

Better email deliverability is the key to a successful email marketing campaign. After all, your subscribers can’t engage or even open the email they never see or receive. At Infotanks Media, we analyze and study email global inbox placement rates so that we can better help our customers improve their subscriber engagements, sender reputation, and finally their email deliverability. We help our customers reach the right inbox and improve their email campaign ROI by getting their email delivered to more of their subscribers.

What is email deliverability?

How you measure the success of your email marketing campaigns reaching the inbox of your subscribers without bouncing or being marked as spam is email deliverability. If you have problems with higher bounces, lower engagement rates or flagging spam filters, you may be encountering email deliverability problems.

So, in this post, we will describe the top 5 things that you may be doing that are killing your email deliverability.

We will also discuss a quick solution that you can easily implement to build better sender reputation and improve the overall success of your email marketing campaigns.

How to identify if you have a deliverability problem?

  • You see an increase in email bounces.
  • You’re being blocked at a mailbox provider.
  • You’re experiencing a drop in engagement rates like opens and clicks.

The email deliverability landscape is always changing, and it is getting even harder to reach the inbox of your subscribers. Email deliverability and inbox placement affect the failure or success of your email marketing campaign, and finally the ROI of your email marketing program.

Following are the top 5 factors that affect email deliverability;

1.  Email Sender Reputation

Email sender reputation is a score assigned by an internet service provider (ISP) to a sender (an organization that sends email). It is a critical aspect of your email deliverability. The higher score you have, the higher are the chances that an ISP will deliver your emails to your subscriber’s inbox on their network. On the other hand, if your score reduces to a certain threshold, the ISPs may send your emails to your subscriber’s spam folder or may even reject them instantly. These several factors that can go into determine your score that may include, but not necessarily limited to the following:

  • The total numbers of emails sent by the sender.
  • How often the sender emails hit the spam traps set by the ISPs.
  • How many subscribers mark the sender’s emails as spam or complain to the ISP about the messages.
  • The sender’s inclusion on different blacklists.
  • How many subscribers open, forward, reply to, and delete the sender’s emails, as well as click the links inside them.
  • How many of the sender emails bounce because they were sent to unknown people or for some other reasons.
  • How many subscribers unsubscribed from the sender’s subscriber list.

Each ISP decides which factors to include in assigning a score to the sender reputation of a sender, and how much it weights those factors to calculate the reputation each sender that sends email to their users. So, a sender may have different sender reputation score for different ISPs. And when a sender uses several domain names and sends emails using different IP addresses, each one of their domain will have its own sender reputation score.

How to protect email sender reputation?

It is very important to follow the best practices to ensure that your email sender reputation score is as high as possible.

Maintain your email list

Clean your email list periodically to remove invalid email addresses and any non-responders. Higher bounce rate can decrease your email sender reputation. So, maintaining a healthy email list will go a very long way to successfully achieve better email deliverability rates.

Monitor your email delivery

Regularly track your email deliverability rates by keeping a close eye on your bounce rates and engagement rates like email opens and email clicks. And with periodic monitoring, you can easily identify any potential problems before they occur.

Implement an IP warm-up plan

The best approach to build a good sender reputation with ISPs is to gradually increase the threshold of email campaign volume over a period of time. As the last thing that ISPs wants to see is a new sender sending a huge volume of emails to their network.

Make your emails interesting and clickable

The way your subscribers interact with your emails is critical to your sender reputation score. So, offer then destinations to engage and offer reasons to your subscribers to open your emails and take the desired action. As if you come as spammy across ISPs, it can harm your email sender reputation score.

The goal here is that you should consider your email sender reputation in the same way you think about your professional reputation. And your email sender reputation works in the same way. Protect your email sender reputation as if your organization’s success depends on it.

2. Email List

Email marketing is all about the quality of your email list and how it is managed over time.

You can easily authenticate your sends, test your subject lines, and optimize for mobile, but the end result is that if your email list is not created and maintained properly, your email marketing campaigns may never make it the inbox.

Check and verify your older email list to weed out erroneous or inactive addresses before sending email campaigns to them. And if you are switching your ESP or has a significant lapse in sending email campaigns, start by sending email campaigns to your most active subscribers and monitor the result to better understand their engagement with your company. And if you receive high hard bounce, unsubscribe, or spam complaint on those email campaigns, then you should verify this remaining email list to take other steps to resolve this issue effectively.

Any email list can easily go bad over time, even the best ones. The people that legitimately subscribed to your email list can easily become uninterested in your emails. Your email list volume or email send frequency may not be the correct fit, some email addresses on your email list could just turn into inactive email addresses or your content may not be on as sharp as it was earlier.

Monitoring and maintaining your email list for the changes in the key performance metrics like opens, clicks, bounce, unsubscribes, spam reports, etc,  is critical in identifying actual issues and then helping to maintain balance and the quality of your email list.

How to maintain a good email list?

A re-engagement email campaign is one of the best ways for an email list that is suffering from low engagement rates, high spam complaints or if you just want to ensure that your email list is filled only with your most engaged and active subscribers.

The main idea here is that you send a series of re-engagement email campaigns to your inactive subscribers for the purpose of re-engaging those subscribers and at the same time identifying the subscribers that are truly not interested in your email marketing campaigns.

3. Spam Complaints

Spam complaints are basically reports that are created by the email recipients by clicking on the “report spam” button for the emails that the recipient think is spam and don’t want in their inbox. It’s critical to properly understand how spam complaint works and how to avoid them as even the legitimate senders get spam complaints.

An email sender that receives a high number of spam complaints, their next email campaigns could be blocked by the ISPs. And as a result, your subscriber that actually wants to receive your email won’t hear from you.

When your subscriber hit the “report spam” button, the mailbox providers like Gmail, AOL, Yahoo, etc, and the ESPs like, SendGrid, MailChimp, GetResponse, etc, receive a notification.

The bad news is that the email senders even with a small number of spam complaints are automatically blocked by the mailbox providers.

How spam complaints are made?

Most mailbox providers include a “report spam” button in the inbox that enables recipients to report email senders that the recipient considers as spam. Below is an example of a “report spam” button in the inbox of a Gmail email account;

The recipients click on the “report spam” button for many reasons. It could be that the recipient is confused about who you are, or it could be because they just can’t find the unsubscribe button, or the reason why you are emailing them, or something else.

Tips for preventing complaints

The best ways to avoid your emails being marked as spam are the following:

  • Don’t overwhelm your subscribers with too many emails.
  • Don’t send so few emails that subscribers don’t remember signing up.
  • Let your subscribers know how often you’ll be sending.
  • Keep content relevant by using segmentation, personalization and dynamic content.
  • Set up a custom domain, so the domain used in your tracking links matches the one in your from address.
  • Make sure that your “From” details mention the business the email is coming from.
  • Use a confirmed opt-in list to stop fake sign-ups, bots and spelling errors from sending your emails where they’re not wanted.
  • Send engaging emails that offer value to your subscribers.


4. Spam Traps:

The spam traps are used by blacklist providers and inbox providers to identify malicious email senders. But, usually, even the legitimate email senders that have poor data hygiene or follow poor email list building practices gets identified as malicious email sender by inbox providers and blacklist providers.

Spam traps look just like real email addresses that are created by the inbox providers and blacklist providers, which doesn’t belong to any real person, neither is it used for any communication. The only goal of a spam trap is to identify senders and spammers failing to utilize proper list hygiene.

Why spam traps are critical to email deliverability?

Based on the type of spam traps having just a single spam trap on your email list can affect your ability to send your email campaigns straight to the inbox of your subscribers.

When you send emails to spam traps, it is considered as an identifier that you have followed bad practices to create your email list, or the very least; you didn’t clean your email list properly. Meanwhile, to inbox providers and the anti-spam organizations, it makes you look like a spammer that could affect your senders reputation. On the other hand, email senders with a bad reputation may not be able to get their email campaigns delivered to the inbox of their subscribers.

How does a spam trap end up on a mailing list?   

To better understand how a spam trap can end up on your email list, it is very critical to understand the various types of spam traps that are currently being used. According to Laura Atkins, email deliverability expert and owner of Word to the Wise, the most common spam traps are the following;

Pristine traps

Pristine traps are the email addresses that are published on public websites but are hidden so a normal visitor cannot see them. The only people that can find these email addresses are those that use bad data collection processes like, scraping the websites for anything that looks like an email address. And if you have collected email addresses by scrapping them from the websites, you may have easily been a victim of a pristine spam trap.

Recycled Traps

Recycled traps are the email addresses that were once used by real people that became abandoned and at some point were turned into a spam trap by the inbox provider. When an email address is not being used, inbox providers will deactivate it after a certain time.

When an email sender sends emails to these addresses, the inbox providers return a hard bounce that is a signal to the email sender to delete these email addresses from their email list. Many email senders honor the request and remove those email addresses, but some email senders choose to neglect this request and continue to send emails to these email addresses.

Converting abandoned email addresses into spam traps is the response from the ISPs to irresponsible senders. And after some time the abandoned email address won’t return a hard bounce but becomes an active spam trap that identifies anyone sending email to this address as an irresponsible sender.

You can easily run recycled spam traps on your lapsed subscribers on your own email list when you don’t email them often. The chances are that you could hit a spam trap just because you haven’t sent an email to your subscribers for a long time and so never received that bounce.

There few more ways you can hit the spam traps. Example, a user that wants to fill your form (like forms on gated contents) but don’t want to receive email from you can fill your forms using a made-up email address. Or, someone may accidentally misspell their email address (like a typo) that could easily be a spam trap.

How to fix spam traps problems?

Spam traps are purposely designed to identify email senders that practice bad email list building techniques. So, you cannot find a publically available list of spam traps that you can use to identify spam traps on your email list and then delete it.

The only way to identify spam traps on your email list is by analyzing the quality of your email list.

Since spam traps neither belongs to a real person nor is it used by a real person, so they won’t behave like your engaged subscriber. And as a result, launching an email campaign to ask your current subscribers to confirm their continued interest in receiving your emails is a healthy approach to separate your engaged subscribers from the ones that didn’t confirm and could be spam traps.

Meanwhile, even if you manage to identify and remove the spam traps on your email list, you have just treated the symptom and not its cause. You need to truly understand how spam traps end up on your email list and restrategize your list building approach to avoid any spam traps finding their way to your email list.

5. Getting Blacklisted

Blacklists are a list of the IP addresses or senders domain address like www.example.com and servers that have been identified sending spam emails. Currently, there are more than a hundred blacklists for various purposes and you should stay away from every single one of them.

A full inbox or a bad email address can cause an email to bounce, a simple typo can easily send the email to the wrong person or make their way to a spam trap, or a blacklist can easily prevent it from reaching the intended inbox.

The occasional bad or typo email address can very easily happen to any email sender and can be easily fixed. Although, when email senders end up on any blacklist, it is pretty serious.

What is an email blacklist?

Blacklists are real-time lists that identify domains or IP addresses that have been identified to send spam emails. These are used by ISPs, anti-spam vendors, and free mailbox providers to avoid spam entering into their network. The email senders or the ESPs can easily find their domain(s) or IP(s) multiple blacklists depending on the volume and quality of the emails sent by them and the quality of email lists they have sent to.

The operators of one of the biggest blacklists, Spamhaus that has developed simple graphics to make it easier to understand when and how a blacklist interacts with an email. An email goes through a few tests to identify whether it should be sent to the inbox or should be considered as spam.

Since blacklists are one of the many methods used to identify whether an email is a spam or not, the true rejection of the email comes down to the policies of the ISP.

How companies end up on blacklists?

Bad email lists and high spam complaint are all that it takes for a domain or IP address to end up on a blacklist. The following can lead to blacklisting;

Spam complaints

When the recipients click the spam button it leads ISPs to think that your email list hygiene or your email content is bad. It can happen even to the opted-in and clean email list and is counted as a spam complaint.

Bad lists or addresses

A lot of email bounces are a tip to the ISPs that your email list may not be updated or opted in. Many blacklists use spamtrap addresses to identify spammers.

A surge in list size

A good email list grows over time as new people choose to subscribe to receive email from you. And when the size of the email list increases by a lot in a short period of time, most ISPs will think that the email list has been purchased.

How to avoid blacklists?

Follow the following practices to stay away from blacklists;

Email content

Make sure you are sending the content what your subscribers are expecting from you and make it more relevant to them by personalizing the whole content.

Good email lists

Maintain your email list hygiene by removing bounced email addresses or the email addresses that are old and have not shown any engagement.

What to do if you end up on a blacklist?

Just don’t panic as there are more than hundreds of blacklists and there’s a good chance that your domain or IP address is listed on any one of them.

Although, if you find yourself on a blacklist, it could be a signal that something is not right. If your domain or IP address is flagged and added to a blacklist, you will have to contact the list about being removed from the blacklist.  The major blacklist organizations have information on their website about how to be removed from their list. The process is quite simple; just ensure that you do what they ask to clean your email list. To see whether your domain or IP address is on a blacklist, go to MX Toolbox.


Your email reputation is what helps get your emails to your subscribers’ inboxes, so be scrupulous about your email content and how you build your lists.

Just follow the methods explained in this article to maximize the deliverability of your emails. Your engagement stats will skyrocket.

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