Send It: How Reputation Affects Email Deliverability

Pressing the send button can send a sense of panic into the mind of an email marketer. Did I check all my copy? Do all my links work? Was that the right segment? How will it perform?  

Recently, we talked about what email deliverability is and why it’s important. In the coming weeks, we are going to continue to review all the aspects of deliverability that affect your email campaignsIt’s our job here at Return Path from Validity to curb that panicgiving you the confidence tSend It 

While reaching the inbox to engage subscribers is a main goal of any email program, getting into the inbox isn’t so simple. There are many challenges that can block you from accessing to your subscribers, the biggest of which is your reputation as a sender. 

What is sender reputation?
Sender reputation is a calculation of all previous actions taken by a sending IP address, both good and bad. An incoming sender’s reputation allows mailbox providers to access who is trying to reach their inboxes and judge whether or not to deliver the incoming mail to the inbox or the spam folder.  

What contributes to your reputation?
There are hundreds of signals that factor into your reputation. Some can help boost your standing, while others harm your ability to reach the inbox. Below are some of the top elements mailbox providers are evaluating and you need to be paying attention to before they damage your deliverability.  

Unknown users: An unknown user is generated when a sender deploys mail to a recipient that never existed, is no longer active by choice, or was abandoned by the end user. Mailbox providers send back a bounce code to senders to inform them that these addresses are no longer active and should be removed from a sending list. 

Spam traps: There are two types of spam traps. Pristine traps are email addresses created for the sole purpose of catching spammers. These addresses were never owned by a real person and are often found as embedded links hidden in the background of websites. Recycled traps are email addresses that were once active addresses but have since been abandoned and are no longer in use. After spending time as unknown users, mailbox providers convert these discarded addresses into spam traps to catch senders who continue to send to unengaged senders. The purpose of a spam trap is to identify senders with “spammy” behavior. Sending to spam traps will drastically reduce your deliverability.  

Complaints: Complaints are end user spam complaints that are calculated against the amount of mail you have sent for the past seven days. A complaint could be produced when an end user clicks on the “spam” or “junk” button within their inbox.  

Disengaged Subscribers: Having a large portion of subscribers that don’t open or interact with your email consistently tells mailbox providers their users are not interested in your content and are unlikely to miss it. To provide a better experience for their users, mailbox providers incorporate prior subscriber engagement into their filtering decisions.  

Blacklists: Backlisting refers to a list of IP addresses that spam filtering companies, mailbox providers, or anti-spam organizations report as “known” sources of spam. Frequent spam traps hits or complaints might prompt a blacklist organization to add your IP to a blacklist. When evaluating an incoming sender, mailbox providers will check these lists to see if the IP address appears. If it does, they may decide deliver the blacklisted senders mail to the spam folder.  

These elements and more can keep you from your subscribers. Learn more about how Return Path from Validity can help you “send it” with confidence and effectively reach and engage subscribers by clicking here.

How Important is Reputation for Reaching the Inbox?

Much like with when conducting any interaction, reputation is important. When you are searching for a new restaurant to eat at or a new doctor to visit, looking up reviews helps you to choose where to go. Mailbox providers incorporate a similar tactic by evaluating the reputation of incoming senders to determine which messages to accept into their mailboxes.

Why is reputation important?
A mailbox providers job is to provide a quality email experience to their users or risk losing their customers to a competitor. This means delivering the messages they want and protecting them from the mail they don’t. To ensure they are filtering the right messages to the correct folders (inbox vs spam), mailbox providers rely on reputation calculations.

What influences sender reputation? 
There are many different elements that can influence a senders reputation. In fact, each mailbox provider has their own unique reputation formula—which they, unfortunately, don’t disclose publicly. But while each calculation differs slightly, the elements they look at are all the same. Namely, anything that represents “spammy” behavior (complaints, spam traps, unknown users, blacklists, etc.,)

How does reputation impact deliverability?
In our recent study—the 2019 Sender Score Benchmark— we looked at the relationship between reputation and deliverability. We measured reputation using our own reputation calculation system—Sender Score.

Sender Score is a numerical score (from zero-100) for your IP address which operates much like a credit score. The higher the score the higher the reputation. It incorporates similar criteria that mailbox providers use in their own calculations to give senders an idea of how their program is being viewed.

The graph below shows the relationship between Sender Score reputation and deliverability at AOL, Gmail, Yahoo, and Microsoft. As you can see: as reputation increases, deliverability increases at all four mailbox providers.

How to strengthen and maintain your reputation.
Low reputation as a result of “spammy” behavior will see your messages blocked from the inbox. To build and maintain a strong reputation, try the following:

1. Monitor your reputation
Your sender reputation constantly changs as a result of your sending activities. It’s important to know if, when, and why your reputation declines so you can immediately address any issues and limit the impact on your program. Before you send a new campaign, look up your latest reputation score for free at  to make sure your latest campaign will reach your subscribers before you send.

2. Keep your list clean
Spam traps, unknown users, and unengaged subscribers can have a detrimental impact on your email program. Ideally, you should run your list through a list hygiene service, which will validate whether the email address belongs to an active person. Alternatively, you can suppress and remove users who have not engaged with your email program within the last 60 days. This will help you identify addresses that could potentially harm your reputation.

3. Sign up for feedback loops
Having complaints can severely impact your reputation. Immediately address complaints by signing up for feedback loops. Each mailbox provider offers its own feedback loop service. Identify which ones are valuable to your program and how to sign up in our post: What is a Feedback Loop.

4. Identify where complaints are coming from
Reacting to complaints is only the first step. If you don’t know the cause, the rest of your subscribers are likely to issue their own complaints. By identifying where your complaints are coming from, you can discover what parts of your program need to be fixed to limit subscriber dissatisfaction.

5. Check for blacklisting
Mailbox providers include blacklisting in their filtering decisions, so it’s important to know immediately if you are blacklisted and where. Make sure you regularly check your IP address on a blacklist lookup.