How to send to dormant subscribers

How to send email to dormant subscribers is a common question we get from marketers. A general guideline used for defining a dormant subscriber in the email industry is 90 days of inactivity (no opens, reads, clicks, or conversions). This of course may be different depending on the frequency you send email and your business model. 

You may desire or be required to send to dormant subscribers for the following reasons: 

  • A legal requirement. You may have a legal notice to send due to a prior product purchase or service agreement.
  • A new product release. Subscribers may have at one time indicated they wanted to hear when your next product was going to be released, but went dormant in the meantime with your regular marketing email.
  • Internal request from management to see if you can help to increase sales. This happens a lot around the holidays.

Return path does not recommend sending to dormant subscribers unless it is a legal requirement or as part of a win-back campaign when they first stop engaging with your email (recently dormant). Depending on the age of the dormant subscribers, the older they are, the more likely they are a spam trap or an unknown user. Sending to a large number of spam traps or unknown users can harm your sending reputation and cause deliverability problems. Also, because mailbox providers factor engagement into spam filtering decisions, sending to dormant subscribers is likely to suppress engagement metrics, which could lead to deliverability problems. 

If you need to or decide to send to dormant subscribers, follow these guidelines:

  • Consult with your legal counsel about any data, privacy and sending laws that may prohibit you from sending to a dormant subscriber.
  • If you have a legal requirement and you can’t follow any of the steps below, consider sending your email from a shared IP or a third party email sender to help protect your sending reputation.
    • If you can’t send from a shared IP or third party sender, then try to spread out the volume over time as best you can and monitor results. You may see short term deliverability problems, but they will normalize once your sending metrics return to normal levels.
  • Segment your dormant subscribers into recency buckets. The size and time frame of these buckets may differ based on the number of subscribers as well as their age of dormancy, so adjust as needed. A guideline you can use is 90-120 days (recently dormant), 120 - 180 days, 180 days - 240 days, 240 days to 360 days, and 360 days or older.
  • Determine the number of subscribers in each segment.
  • Determine how they went dormant. Not engaging with your email is different than a suppression list which is based on unsubscribe requests and complaints. Do not send to a suppression list of people that have unsubscribed or complained at any time in the past.
  • Determine if you can also segment these subscribers based on other data such as prior purchases or demographics.
  • Send the list of dormant subscribers through a list validation service to help weed out unknown users, malformed domains, and possibly spam traps. There is no guarantee that a list validation service will remove all of these addresses, especially spam traps.
  • Like with any email campaign, develop a basic plan for sending. Determine what your message, content and offer will be for each segment as applicable. A targeted message is likely to have higher success getting someone’s attention.
  • Determine success metrics for each segment. You should expect lower engagement metrics and could see a spike in complaints, unknown users and spam trap hits. Cut your normal engagement expectations in half as a general starting point and adjust over time as you learn more about how the dormant subscribers react.
  • Set up monitoring through Inbox Monitor and Reputation Monitor to track deliverabilty, sending reputation, and blacklistings
  • Make sure you can get access to SMTP bounce logs or reports so you can monitor for an increase in throttle messages, spam classifications, blacklistings, or blocks. Contact your ESP or email administrator to find out how to get access to these logs or reports.
  • Send a test to a small segment to gauge reactions. The size of the test will be based on the total number of dormant subscribers.
    • Pick a cross-section of subscribers using your recency and other segments as applicable.
    • Be conservative. Start with a small test of 100 subscribers.
    • If results are positive or negligible, send a few more tests, doubling the volume each time.
  • Spread out your send over several days or even weeks depending on the volume and send in small increments over time throughout the day. You want to minimize any negative metrics against your normal email traffic to reduce the likelihood of encountering deliverability problems.
  • If you start seeing poor results or deliverability problems, stop sending and reassess your approach.
  • If you continue to see poor results, reconsider your decision to send to dormant subscribers and try to focus more on winning them back prior to or at the point where they stop engaging with you.
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