IP reputation
What is an IP address?
An IP address is a unique string of characters assigned to every device connected to the internet; for example, 12.135.45. This address determines where the data should be sent to and received from, much like a home address. An IP address is necessary to communicate with any website or application online. When you visit a website, your device uses the website's IP address to locate and communicate with it.
What is an IP reputation?
Just like neighborhoods develop a reputation based on their proximity to schools, hospitals, and grocery stores, as well as their crime rates, IP addresses build a reputation based on their past email activity.
An IP reputation refers to how trustworthy an IP address is as determined by Email Service Providers (ESP) and spam filters. When a mail server receives an incoming email, it checks the sender’s IP reputation before deciding whether to accept, reject, or mark it as spam.
This is evaluated based on the IP's past activity, like engagement rates, spam complaints, and bounce rates. An IP with consistently good engagement rates and fewer spam complaints is considered more trustworthy than one with frequent bounces and higher spam rates. Moreover, an IP reputation isn't based on the feedback from a single IP. It's built from the interactions with all recipients that the IP sends emails to.
Types of IP addresses used
Email service providers use two types of IPs:
- Dedicated IP: It’s assigned exclusively to a single sender and is used by businesses or large volume senders. Because a single sender uses it, the reputation is influenced by that sender only. The threshold of being assigned a dedicated IP varies with ESPs.
- Shared IP: A shared IP address is used by multiple senders, usually small to mid-sized businesses, who may not send emails in high volumes. In this setup, the reputation of the IP is determined by the sending behavior of everyone using it.
If you’re unsure of which category to pick, you can refer to our article on shared and dedicated IPs to better understand how they work and determine the right fit for you.
Factors that affect IP reputation
There are multiple factors that affect IP reputation. These include:
- IP category: The category of IP you’re using, whether dedicated or shared.
- IP age: How old or new your IP is. New IPs need to be warmed up gradually to avoid spam classification.
- IP history: Previous record of spam complaints or bounces.
- PTR records: PTR records map an IP address to a domain name. Properly configured PTR records improve the IP's credibility.
- Spam complaints: How often an email sent from a particular IP is marked as spam. Frequent spam complaints can result in lower reputation.
- Bounce rates: The number of times emails sent from a particular IP bounce. High bounce rates can lower the IP's reputation.
- Recipient engagement: How many emails are opened, clicked, or replied to. Engagement metrics are used to gauge if the recipients want and need the email. If the emails receive good engagement, then the sending IP will have a good reputation.
- Frequency: Indicates how often emails are sent out from a particular IP. A consistent sending schedule builds trust and indicates a credible IP. Irregular or sudden spikes in the emails can appear suspicious.
How do you check IP reputation?
If you’re using shared IPs, you can find the sending IP from your recent emails.
- Open the most recent email you’ve sent.
- Click on View Original and look for the following information in the email header:
- Received-SPF: pass (example.com: transitioning domain of example2.com designates 165.173.182.251 as permitted sender)
- Authentication-Results: spf=pass (example.com: transitioning domain of example2.com designates 165.173.182.251 as permitted sender)
Once you have the IP, you can check its reputation using one of the following tools mentioned here. Check the most recent emails because the IPs repeatedly change in a shared pool.
Domain reputation vs. IP reputation
A common question when it comes to domain and IP reputation is in their difference. Although they’re closely related, they’re not the same, and they serve different purposes.
A simple difference between the two is that IP reputation focuses on the IP from which an email is sent. It’s dependent on the infrastructure from where it’s sent and can change when you change the email service provider.
Domain reputation is tied to the domain name that’s sending that email; for example, the company's name. This reputation is independent of the ESP you use. It reflects the brand's sending practice and will follow the domain even if the IP changes.
In general, IP reputation tells email servers where the message is coming from, while domain reputation tells them who is sending it.