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Read rates are one of the most critical measures of success regarding reachability in email marketing. However, if the messages you send don’t reach your audience, you won’t be able to achieve high read-rate levels. Reachability in email marketing is extremely important and can determine whether your email marketing campaigns are successful or not. 

What is Reachability in Email Marketing, Why is It Important?

Many companies assume that 100% of the emails they send reach their audience. Technically, this is impossible since deliverability differs according to many different factors. The user’s computer network settings and email reading habits (opening mail – clicking – deleting – deleting without opening – ignoring) are all factors that influence your reputation, which ISPs will use to determine whether you are a legitimate sender or not. If your reputation is good, your reach will increase, if it’s bad, it’ll be difficult for you to reach your audience through email marketing. To improve reachability in email marketing, it’s essential to understand how email filters work. 

Why are Spam Filters Important?

When it comes to reachability in email marketing, filters organize emails according to certain criteria. At first, the purpose of filters was only to detect spam emails, redirect them to the spam folder or block them entirely. Today, ISPs use filters to categorize emails according to their function, and some may have to do with social media, while others could be related to promotional information.

Whether the email you send falls into the inbox or spam folder of the receiver or is completely blocked, it’ll definitely pass through a filter. Filter technology plays a key role in your success regarding reachability in email marketing. For this reason, being comfortable with filters, understanding how they work, and learning how ISPs are used will increase your success in this channel.

Why Do ISPs Filter Emails?

If you want to understand better how to increase your reachability in email marketing, it’s important to gain insight into how emails are filtered. ISPs are eager to use a spam filter, whether they set up their security system, get help from a third-party company, or combine both. Spam is as dangerous as it’s disturbing. While malicious software (malware) and phishing emails provide high profits for scammers, they can also be extremely costly for ISPs to prevent. Spam filters significantly alleviate the load of the servers since more than 50% of all emails sent in the world are spam. Until the email from the sender reaches the end-user, it’s faced with many filters that affect accessibility and where an email is sent to the inbox. 

What are the Different Types Of Filters?

Until the email from the sender reaches the end user, it’s faced with many filters that affect deliverability. The following is a brief look at these different filters and how they impact reachability in email marketing

Anti-spam Gateway Filters

These filters are physical servers that are included in filter systems, and they can be considered the first assistants of ISPs. Every email that comes to a company has to pass this filter before it reaches the inbox. These filters learn over time and begin to recognise senders.  The only disadvantage of these filters is that they can only examine emails sent to the company and can’t develop by learning about the different types of spam from outside sources.

Third-party Spam Filters

These are filters that are used by different companies that try to separate harmless emails from spam emails with content control and reputation criteria. Third-party filters are involved in the decision-making processes and affect whether the emails that pass through this filter go to the spam folder or into the inbox. Due to the large number of companies using these filters, they learn a lot about spam emails. This provides a lot of information about which emails can be processed and which ones can’t.

Desktop Spam Filters

This is the protection method available on the end user’s computer. This is perhaps the most difficult spam filter to pass, as it can be adjusted to the user’s personal preferences. The most known of these is the Outlook program that uses Microsoft’s SmartScreen spam filter. Regarding reachability in email marketing, this can impact how many of your customers receive your emails versus how many end up in the spam folder. 

What are the Filtering Types?

ISPs have three main filtering types that impact reachability in email marketing. They’re as follows. 

The Source

Spam senders try to defeat the reputation system by changing their IP and domain every time they send an email. However, spam filters perform the filtering process by looking at the sender verification, continuity, and how long sending was actualized from the same IP and domain. ISPs always approach emails sent by new IPs and domains with extra caution. Senders who use the same IP and domain for a long period of time tend to have a stronger reputation and are considered to be more reliable. This can be extremely beneficial when it comes to reachability in email marketing.


The sender’s reputation is calculated using specific algorithms and data analysis. The reputation score is graded from 0 to 100 (Return Path) or 10 to 10 (IronPort). ISPs filter incoming emails according to the reputation score that they receive. The main reputation titles are as follows:

  • Spam complaints
  • Spam trap addresses
  • Message content
  • Volume
  • Blacklists

Repuation is perhaps the most important criterion in determining the reputation score. Keeping the complaint rates low and adjusting the frequency of sending with quality content should be the main goal of every email marketer. This’ll increase reachability in email marketing and ensure that your emails get to the recipient. 


Nearly every element of an email is checked during content analysis. Header, footer, structure, the layout of HTML coding, image sizes used, color and size of the fonts used in the content, URL lengths, subject title, attachment and many other items are the criteria by which the content is viewed while passing through the filter. Content should be written and structured well to increase reachability in email marketing. 

To sum up, spam filters are an important part of any email ecosystem. Without them, millions of spam emails would invade the servers, preventing the system from working effectively. We can call them guarding friends. We’re pleased that they prevent unwanted emails from falling into our inboxes, as well as deliver the messages we need to receive. And again, thanks to the filters, important transactional emails reach us. When increasing the reachability in email marketing, it’s important to use these filters to your advantage.

Why List Quality and Complaints Matter for Reachability in Email Marketing?

In the ideal e-marketing world, your member lists should consist of people who are actively interacting with the content you send and who want to receive messages from your brand. Creating a high-quality list in line with your target audience will be very beneficial when it comes to deliverability.

ISPs track the email inboxes you send to and if you’ve a bad list structure, they can filter your content or block it completely. The three different types of users are as follows: 

  • Unknown addresses (invalid)
  • “spam trap” addresses
  • Inactive users

User spam complaints are also critical for signifying bad list quality and are important in the filtering phase when it comes to reachability in email marketing. 

Unknown Users

Unknown users are made up of addresses that have never existed, memberships that have been terminated by the ISP or ones that have been abandoned by the user. Another known name is “hard bounce”. Since the message sent can’t reach the person, ISPs report 550 error codes. Such addresses should be removed from your list immediately. The ratio of the number of unknown users to the total number of users sent determines the unknown user rate. To enter the inbox will have a low rate of unknown users, this figure should be below 2%. An unknown user rate exceeding 10% will cause serious problems when it comes to deliverability.

Spam Trap Addresses 

“Spam Trap” addresses are email addresses that don’t belong to any real person or institution and are created purely for feed purposes. Mailing to one of these addresses will likely result in surveillance of your IP, and in the worst case, may end up in you being blacklisted. There are two types of spam trap addresses that impact reachability in email marketing:

Reactivated Spam Trap Addresses

Even if your entire data list is made up of members with permission, some addresses may be a “Spam Trap”. The main reason for this is that ISPs convert addresses that haven’t been used for a long time to “Spam Trap” addresses. The reason for this is to encourage email marketers to always have an active audience.

Addresses Created to Catch Spammers 

These addresses are usually embedded in email lists for sale or intentionally embedded in websites to be found by robots. When it comes to reachability in email marketing, it’s important that you’re able to filter out these kinds of addresses. 

What Can You Do to Clean Up Invalid and Spam Trap Addresses?

Now that you’ve a better understanding of how invalid and spam trap addresses can negatively impact your email marketing efforts. It’s important to know how to resolve these issues. The following is a look at what you can do to clean up invalid and spam trap addresses. 

  • Quarantine New Data: Keep your new data list separate until you send a welcome email and receive “invalid” confirmation. 
  • Increase the Easiness of Information Updates: Users can frequently change their email addresses. Easy change of membership information will reduce the number of invalid emails.
  • Use Double Opt-in Permission Structure: The address of the membership should be confirmed by a second email sent to confirm the valid address.
  • Choose the Data Source Carefully: Check the data you obtain from third parties periodically and inquire about where it’s obtained from.
  • Email Your Subscribers Regularly: In general, sending less can cause you to encounter a high volume of invalid addresses. Frequent sending will increase awareness as addresses that haven’t been used for a long time are converted to spam trap addresses.
  • Check Member Activities Regularly: As a general rule, the user who hasn’t interacted with your content for nearly 1 year is no longer an efficient member for you and should be removed from your list immediately.
  • Perform a Simple List Cleanup Operation: You should clear generic addresses like, unusable addresses like, or addresses with obvious typos like @ from your list.

Passive Addresses

Passive addresses, in short, are people who are on your member list but don’t read, click or take any action. Passive members can cause many unwanted consequences when it comes to reachability in email marketing. These emails can be an invalid or spam trap source, negatively affecting your reports and reducing your overall reputation.

The measures to be taken are straightforward:

  • Identify passive members.
  • Actively monitor read, click, and ‘bounce’ figures. Whenever the numbers begin to fall, do the necessary cleaning by comparing them with the original level.
  • Try to identify the data source of passive addresses. Whichever channel or platform it comes from, it’ll be easier to take action.

Using these measures can help improve your reputation and reachability in email marketing and reduce the number of passive emails you send to your audience.

Spam Complaints

The primary purpose of ISPs is to protect their users. For this reason, they attach great importance to their feedback and preferences. If the recipient complains (marks spam) about the email sent, the ISP will consider the e-mail unsolicited and block future submissions. As a result, complaints are one of the most important criteria for a low reputation.

There are 3 ways users can file a complaint:

  • Spam Button: When the user presses the spam button.
  • Postmaster Complaint: When the ISP sends a complaint message to the “postmaster” address.
  • Filter Application Complaint: The user applies to the filtering application or to the blacklists that accept the user complaint.

It’s important to reduce the number of complaints that are filed against you as this can  impact how reliable ISPs see you. Using the tactics mentioned above to clean up your email list and ensure you’re only emailing those who are interested in your offers can be extremely important. This impacts your overall reachability in email marketing and how effective your emails are. 

Maintain a Reachable Email Campaign with SmartMessage Products and Services!

The deliverability services offered by our team here at SmartMessage are able to help you monitor your reachability when it comes to email marketing. Our team will offer a deliverability consultation and also help you throughout the sender score application process. After this, we’ll provide continuous management and support in the form of a monthly deliverability service report which will help you to monitor progress and keep up with your changing score.