Email reputation explained

Billions of emails are sent around the world each day. Some of these successfully land in the recipient's inbox, while others never see the light of day. In fact, about 85% of the email traffic worldwide accounts for spam (Number from March, 2019). As a sender of email, you inevitably want your emails to end up in the inbox. Unfortunately, there is no magical spell that ensures they will end up there. Instead there are many factors that affect email delivery. One of these is your email reputation, which we will discuss in this post.

The reputation system

To decide whether your email is worthy of reaching the inbox, most ISPs and Mailbox providers have a reputation system that classifies you. They do this to protect their users from bad senders and unwanted emails. As a sender, you normally fall into one of these three categories:

Every ISP and Mailbox provider has their own filtering system that influences their delivery decision, and all of them slightly differ from each other. All of them, however, make a distinction between the two types of email reputation that influences your email deliverability. Let's take a better look at these two.

IP reputation and Domain reputation

So while there are different factors ISP and Mailbox providers look at in their filtering system, IP reputation and Domain Reputation are two important ones. They are classified separately by ISPs and Mailbox Providers, but together they account for your overall email reputation.

IP Reputation

IP Reputation is your reputation factored from your IP address. Your IP address is the unique identifying address of your server from which your emails are sent. Whether your emails are using a new IP address, a dedicated IP address or a shared IP address has an affect on your IP Reputation.

If you group IPs together and assign different senders to them, then this is called a shared IP address. With shared IP addresses, there is a chance that the behavior of the other senders either positively or negatively impacts your IP reputation. For senders who send small volumes of email, a shared IP can be beneficial however. This is because they normally will use pre-warmed IPs that have already built up a good reputation. For large senders it can be better to send from a dedicated IP address instead. In this instance they are protected from the behavior of other potentially bad senders. They still need to make sure they have their own sending practices in order though.
MailerQ offers tools with which you can set up IP Pools with dedicated and/or shared spaces.

Domain Reputation

Domain reputation is your reputation factored from your domain. While you can change your IPs and add new ones while leaving the old one behind, your domain reputation is portable. This means that you take your domain reputation with you regardless of which IPs you are sending from. A domain reputation is more specific per sender, a lot of ISPs and Mailbox providers therefore are stricting their filter systems for this type of reputation. If you have a bad domain reputation, there is a higher chance that your emails will end up in the spam or junk folder. Luckily, there are things you can do to prevent this from happening.

You can earn a good reputation

There are three main metrics, next to - engagement rates (such as opens- and clicks), under your control that ISPs generally look at in one way or another. These are:

To keep your spam complaints and unsubscribe rate low, you should avoid using email lists bought from third parties. When you send to addresses that gave explicit permission for it, you have a higher chance of getting your emails delivered. Also, make sure that your unsubscribe button works and send content that your subscribers actually want to receive.

No Blacklist Appearances

If your numbers are high, you increase the chance of ending up on a blacklist. Appearing on just one of the leading blacklists is enough to get you blocked by some ISPs. Senders with low complaints, who don't hit spam traps, and who send email consistently generally don't get blacklisted. However, if you do get blacklisted, having a good sending reputation can help you get off of it quicker.

It takes time to build a reputation

For both IP reputation and Domain reputation it takes time to build it up. New IP addresses and domains don't have any sending reputation yet and therefore are less effective in getting your email delivered into the inbox.

On IP level, a Mail Transfer Agent can offer you a variety of tools with which you can easily warm-up your IP address to increase its sending limits. With delivery throttling, flood patterns or dynamic delivery, you can for example slowly limit the number of messages or connections they accept or slowly increase your sending capacity without harming your reputation.

On domain level, there are a lot of things you can do yourself to make sure you build up a good reputation. A number of these will be discussed during our workshop at the CSA Summit “Understanding the Email Communication Between the Sender and Receiver's MTAs."

In this workshop we will take you through the journey of an email, starting from the sender's Mail Transfer Agent (MTA) to the receiver's MTA. We will cover the way that ISPs are filtering your emails, as well as adjusting the sending parameters on the MTA's side for optimized deliverability (Pause, Limits, decrease the IP number, etc.)

If you are interested to learn more about the interplay between senders and receivers and will be at the CSA Summit make sure to attend our presentation on Friday the 12th of April from 10:00 until 11:00