IP reputation is no longer enough for inbox delivery

IP reputation is no longer enough for inbox delivery

Posted under Email Delivery on July 12, 2017

“Over a period of time, the importance of IP reputation will slowly fade away, and sender domain reputation will gradually acquire more weightage. In near future, all email anti-spams will start measuring the sender domain reputation to decide what to do with an email – whether to put in Inbox or Spam”.

A reputation of the email determines whether or not your email messages will make it to the inbox or land in the spam box.

There are two components that make up your email reputation. These include IP reputation and domain reputation

For over a decade mailbox providers have primarily looked at the IP reputation of the sender when making filtering decisions. However, in the past few years and going forward, your IP reputation will no longer enough make an informed decision about the health of your email deliverability.

Domain-based reputation provides the holistic picture

Nowadays, mailbox providers are factoring in dozens of different variables when making a decision about whether to place your email in the recipient’s inbox or spam folder. And, the most important factor is Sender Domain Reputation.

What is Sender Domain Reputation?

As a sender, you’ll gradually gain a reputation as you send messages over time. The content of the email, frequency, and volume of emails sent, how often are they tagged as junk, spam, bounced, open contribute to the reputation.

A good reputation can be a result of the best practices you’ve been following, on the other hand, you’re levied with a bad reputation when exact opposite happens. Bad reputation may prevent your emails from reaching your audience.

How is the Sender Domain Reputation calculated?

Individual user behavior is the main factor. This is calculated based on multiple factors, such as –

1. Engagement rate: Number of emails a user has received v/s the email open rate

2. Email Read Time: Time spent on an email to read

3. Click Rate: Number of clicks made on the email

4. Reply/ Response Rate: Whether the user replied or responded to the email

5. Sender Compliance: Following the best email delivery guidelines like;

  • SPF

Sender Policy Framework (SPF) is an email authentication standard developed by AOL that compares the email sender’s actual IP address to a list of IP addresses authorized to send mail from that domain. The IP list is published in the domain’s DNS record.

  • DKIM

DomainKeys Identified Mail (DKIM) which was designed to help ISPs prevent malicious email senders by validating email from specific domains.
Phishers and spoofers can be sending an email to unaware recipients by pretending to be a trusted sender. By verifying DKIM records the ownership of the domain is confirmed.


DMARC stands for “Domain-based Message Authentication, Reporting & Conformance.” DMARC is a protocol that uses DKIM and SPF to determine the authenticity of an email message. In order to act on a message, DMARC requires both DKIM and SPF to fail.

  • rDNS

Domain Name Servers (DNS) are like internets phonebook. They maintain a directory of domain names and translate them to Internet protocols (IPs).
rDNS is a method of retranslating an IP to a domain name.

  • Proper MX record

Having a proper MX record will assist you in keeping a track of responses from ISPs and recipients.
An MX record is an entry in your DNS zone file which specifies a mail server to handle a domain’s email. You must configure an MX record to receive an email to your domain.
You can check a DNS MX record using an online tool


6. Business website on the sender domain

Sender domain should have a clear web presence, usually where a customer can sign up. Your sending domain must have a live and working website attached to it. It should not be under construction or a static, non-operating page. The website must have a source of collecting user data.

7. Number of spam complaints

Spam complaints are a direct signal from recipients that your emails are unwanted to the receiver.

8. Number of hard bounces

This is a permanent delivery error caused by an invalid email address (e.g. an invalid email, destination server unavailable). Hard bounces have a negative impact on your sender domains reputation and are blocked by ESPs.

9. Number of spam trap hits

Spam traps are email addresses ISPs use to trap illegitimate senders who add email addresses to their mailing list without permission. If you send an email to any of the spam traps in your mailing database, ISPs might tag you as a spammer, irrespective of the quality of emails you send.

10. Spam score

Spam score is the score given to an email depending on multiple rules. The higher the score, higher is the chance of the message being a spam.
Calculate you spam score here: check your domain’s sender score

Considering domain reputation as a part of the analysis is important for all senders – big and small, irrespective whether you are using dedicated or shared IP addresses. That’s because of majority mailbox providers, who have historically looked at IP address reputation, are now also taking domain reputation and domain-based authentication into account when making filtering decisions.

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Dibya Prakash Sahoo|The Business Guy

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