Track and Monitor Your Reputation using Sender Score

Seed list monitoring is vital for tracking the deliverability performance for your IP addresses, email campaigns and list segments. But, it’s important to combine sending reputation metrics (e.g. Complaint Rate, Unknown User Rate, Spam Trap hits) with deliverability metrics to help you troubleshoot your deliverability problems and measure the success of your email program.

Return Path’s recent Sender Score Benchmark Report and infographic talks about what it means when a sender loses its ability to communicate with its customers as reflected by its sending reputation. Senders that have a good sending reputation experience better deliverability than senders that have a poor sending reputation. It’s that simple.

How do you determine the sending reputation of your IP addresses?

The answer: Sender Score. Like a credit score, your IP addresses’ Sender Score is an indication of its trustworthiness as an email source. Return Path's Sender Score reputation rank (scores from 0-100), compiled through our cooperative reputation network, provides access to data that ISPs and other email receivers can use to determine whether to accept or reject email. Look up your Sender Score.

How do you use your sender score to help monitor your sending reputation and deliverability?

Using Return Path’s Reputation Monitor allows you to track your Sender Score and understand the primary risk factors that lead to a good sending reputation. The primary risk factors involved in calculating your sending reputation are:


  • Complaint rate: This is the rate of end user spam complaints against the mail you have sent. Spam complaints are generated when a subscriber clicks on the “this is spam” button. Look for spikes in the complaint data and determine if they correlate with a specific campaign, email template or list segment. Return Path data shows that email senders need to keep their complaint rates at .1% or below to avoid a negative effect on your Inbox Placement Rate.

  • Unknown User rate: The Unknown User Rate is calculated by dividing the number of unknown users by the attempted volume. An Unknown User is a user that does not exist within the receiving system. The industry standard for an acceptable unknown user rate is 10%; however, deliverability problems start to occur at 5%. Our best senders maintain unknown user rates below 2%.

  • Spam Traps: The number of spam traps hit over a period of time. Spam Traps are email addresses created solely to capture spammers and are a symptom of poor list acquisition or list hygiene practices. An ISP may assume you are a spammer and filter your email when you send email to one or more spam traps. Review your list acquisition and list hygiene practices and ensure they are focused on obtaining and maintaining a high level of list quality.

  • Blacklists: A blacklist is a list of IP addresses that ISPs, spam filtering companies, or anti-spam organizations create and maintain to assist with the filtering or blocking of spam. The blacklist owner will publish the list and allow other organizations to use it to help them filter or block email. Ensure that your IP address doesn’t end up on an important blacklist like Spamhaus or Spamcop. Many times, your IP address will get listed for excessive spam complaints, unknown users or hitting a spam trap on their network.

  • Sender Rejected: Rejected mail is taken from the incoming SMTP logs of participating ISPs and is defined as any message blocked during the SMTP conversation. A high rejected rate means your email is being blocked by an ISP. Our best senders maintain rejected rates below 1%.


Using your sender score can help you determine the overall health of your email program, and our latest infographic also shows you the effects these reputation measures have on your sender score.  When used with a robust list and IP segmentation strategy, it can be a powerful tool in your toolbox for improving your deliverability and increasing your overall email ROI.