Data Overload? Focus On These 3 Metrics that Drive Sender Reputation

In the world of email marketing, engagement is king. But who (or what) is queen? When I think about engagement, the obvious complement is sender reputation metrics—to be successful, you need both! And because Sender Score is typically used as a leading indicator of sender reputation, the most important sender reputations metrics are those that influence Sender Score.

Many of the conversations I have with my clients revolve around data overload: where to focus time and attention in order to make the biggest impact. I’ll tell you what I tell them: take a deep breath, and focus on just three key metrics.

What is Sender Score?

First of all, it’s important to understand Sender Score. Like a credit score, the higher your Sender Score, the better your reputation as a mailer. The score is determined by factoring a sender’s performance across key reputation measures important to both ISPs and recipients of email. More than 60 metrics are taken into consideration, but the top measures that factor into your Sender Score are below:

  • Complaints
  • Spam traps
  • Unknown users
  • Volume
  • Infrastructure
  • Sender rejected
  • Messages filtered

When it comes down to it, three metrics influence deliverability more than any others: complaints, spam traps, and unknown users. We’ll take a detailed look at each of these individually.


What are complaints?

Complaint rate indicates how often your subscribers mark your mail as spam or move it to the junk folder. Mailbox providers calculate complaint rates by dividing the number of complaints by the number of delivered messages. If mailbox providers believe your complaint rate is too high, they will filter your email to the bulk folder, or block it. A high complaint rate is the biggest cause of delivery problems and poor sending reputation.

How can I avoid complaints?          

  • Tell subscribers the type of content they will be getting from you, how much they’ll get from you, and how often—and stick to those promises.
  • Only acquire subscribers through acceptable means of consent.
  • Send a welcome message highlighting the good content subscribers will get from you.
  • Give subscribers a preference center so they can choose what they want to receive.
  • Create customized, targeted emails (including content that is not promotional).
  • Make it easier for subscribers to unsubscribe than complain!

How do I prevent future complaints?

  • Identify where complaints are coming from:
    • Sign up for complaint feedback loops. Use this feedback to learn why your subscribers marked your messages as spam.
    • Do something about those complaints.
    • Remove any complaining subscribers from your list.
  • Learn why complaints are happening so you can stop them in the future:
    • Search your list for complaint hotspots (customer segments, campaigns, etc.)
  • Review your acquisition and permission practices in these hotspots, as well as your sending volume and frequency. Have you sent email that subscribers didn’t want? In a time frame they didn’t expect?
  • Once you discover complaint hot spots, and the actions causing these complaints, change your practices. This may mean getting rid of a poor data partner, or retiring a campaign.
  • As your complaint rates drop over time, continue following best practices, keep an eye on feedback loops and complaint hot spots, and take action to reduce complaints.

Spam Traps

What are spam traps?

Spam traps are email addresses activated by mailbox providers and others to find senders with poor data hygiene and collection practices. Hitting spam traps will lower your sending reputation, and may get you blacklisted.

  • Recycled trap: abandoned email addresses mailbox providers recycled into spam traps.
  • Pristine trap: email addresses or domains created by mailbox providers or spam trap operators to catch senders who harvest emails. These emails were never used to send or receive mail.

How can I avoid spam traps?

Send email only to consenting subscribers, maintain good list hygiene, keep a sound infrastructure, and maintain secure systems and databases. Here are some tips:

  • Reject requests to opt in from malformed addresses (i.e., [email protected]), [email protected] or [email protected] addresses, and role accounts (i.e., [email protected]).
  • Use a confirmed or double opt-in process.
  • Have a process for handling hard and soft bounces, and removing old and/or inactive subscribers.
  • Do not purchase, rent, or lease email addresses from third-parties.
  • Do not perform email appends.
  • Regularly monitor feedback about spam trap activity on spam trap and blacklisting sites.

How do I prevent future spam trap issues?

Find out which addresses are spam traps and remove them:

  • Segment your list into small groups, send an email to each group individually to discover where the spam trap(s) are hidden, and remove any traps found. Some tools like Reputation Monitor and Certification, will provide you with results on where the spam traps on your list are, so you can more quickly and effectively clean up your list.
  • Discover any security or infrastructure breaches and fix those problems:
    • Do a full audit of all machines on your sending network to find any compromised machines; fix any problems.
    • Make sure asynchronous bounces (bounces received after the Mail Transfer Agent [MTA] confirmed the email as sent) are disabled for all receiving MTAs on your network.

Learn why you are hitting spam traps so you can stop doing this:

  • Review your bounce management, list collection practices, and data partners to see if these factors are allowing you to collect spam traps or keep old addresses around that may be turned into spam traps; fix any problems found.

Unknown Users

What are unknown users?

Unknown users are addresses on your list that are either misspelled, have been abandoned, or never existed. Aim to keep your unknown user rates as low as possible; rates over .05% may affect deliverability at many mailbox providers. You can Identify unknown user, post campaign send, through your SMTP Error Codes (e.g., 5.x.x- Unknown User).

How can I avoid and remove unknown users?

Follow many of the same best practices for removing unknown users as for removing spam traps, such as:

  • Monitoring feedback loops.
  • Monitoring your own data and looking for hot spots of unknown user rates by mailbox provider, campaign, or customer segment.
  • Asking recipients to confirm their email addresses.
  • Removing inactive subscribers.
  • Reviewing your email collection, sending, and hygiene practices for any problems.
  • Removing addresses that return a hard bounce.

Now that you have found your focus, leverage your sender reputation metrics to complement your engagementparticularly complaints, which are a huge indicator of both engagement and reputation. Together the “king” and “queen” of the email marketing world can help you maximize return and increase inbox placement.

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