Email Sender reputation

Your email sender reputation is a crucial aspect in your quick email acceptance from the ISPs (Inbox Service Providers) and Inbox (Main Inbox, Promotions, Updates) delivery. It is calculated by each ISP on a 30-day rolling calendar.

To ensure your messages are not deferred and emails reach the users’ inbox, you need to ensure you follow Email Best practices, monitor your reputation and take action to correct it in a timely manner.


1) Monitor your campaign performance

Some of your email metrics can help you understand your current reputation and evaluate your inbox placement. The more positive signals ISPs see for your emails, the higher your reputation is. Negative signals hurt your reputation, so you need to watch out for early signs of issues.

Positive signals:

  • Consistent sending calendar - the amount of emails you send on a daily and monthly basis needs to have a consistent pattern, avoid “surprise” blasts or long periods of silence 
  • High delivered per sent rate - having most of your emails delivered shows your user list is active and clean
  • High unique open rate - open rates vary across industries and verticals, but the higher your open rate is, the better - your users show the ISP that your emails are wanted. Make sure you allow 12-24 hours after the email is sent to start measuring open rates
  • High click rate - same as open rate. 
  • Other user actions like starring a message, moving it to a separate folder, replying or forwarding it

Negative signals:

  • Inconsistent calendar - huge spikes in volume (more than twice your largest send for the last 30 days), long periods of inactivity. If you need to send a large amount of emails which exceeds more than double your usual highest volume, you need to break down the campaign into smaller increments and send it over a few days (you can refer to the IP warmup schedule). If for some reason you haven’t been sending at all (or very few emails) for a long time, you may have to start your IP warmup from scratch. 
  • Low delivered per sent rate, combined with high bounce rate - having too many bounces may be a signal of poor data collection practices or spam blocks placed on your domain/IP. 
  • Low open rates - If your users do not open your messages, they indicate to the ISP that your emails are not wanted, and they will eventually start landing in spam
  • High unsubscribe rates - same as above - this shows the ISP that your emails are not wanted. 
  • High Spam complaint rate - this hurts your reputation the most. If too many users start reporting your emails as spam, the Inbox providers will start filtering all of your messages. 
  • Other user actions like deleting without reading, filtering to Trash, listing your From address in a personal block list.

2) Monitor your reputation and IP health

Besides the email metrics, there are a few more tools that can help you understand what your reputation is. 

3) Measure your actual Inbox placement

Your actual Inbox placement can only be measured via seed testing. Such a feature is not available in Leanplum. Most marketers use 3rd party paid tools (Return Path, Email on Acid, Litmus) for this. To send emails to a seed list, you need to upload your list as users in Leanplum. Make sure they have all the necessary attributes (email address, User ID) as well as a custom attribute that will help you distinguish them from the rest. 


Reach out to if you need help understanding your reputation and campaign performance, or if you notice a significant drop in email metrics.

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