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Engagement Guidelines and Re-engagement Strategy

Engagement Guidelines

Nearly every major mailbox provider relies heavily upon subscriber engagement to determine whether mail is delivered to the inbox, spam folder, or rejected entirely. For optimal inbox delivery rates, mail should be targeted primarily to recipients who have actively and recently engaged with your email. To help inform your decisions around audience targeting, we’ve built out a list of recommendations depending on when the recipient last showed engagement.

Please note that these guidelines apply specifically to engagement with an email (open or click). Purchases, site visits, logins, etc. do not have any direct impact on mail delivery and as such are not included in these recommendations. For example, a recipient who made a purchase 3 months ago but last opened an email 13 months ago would fall into the 12-14 month category. 

  • 0-6 months: Recipients who have opened or clicked an email within the past 6 months are typically safe to send. These recipients present minimal risk of blocklisting or rejections by the mailbox providers. We recommend this group of recipients make up the core of your promotional mailing lists.

  • 6-9 months: Increasing the engagement window to 9 months represents a slight increase in risk, but these are still generally safe to send without limitation.
  • 9-12 months: A bit more risk is involved here, but these are also typically safe to include as part of your audience. At this longer engagement window, you’ll want to be mindful what percentage of your total volume falls into the 9-12 month category. We recommend keeping that number around 5-8% of your total volume for a given day.

  • 12-14 months: Recipients who haven’t opened in more than a year become much more risky to send. These addresses have a much higher likelihood of being rarely used, abandoned, or even repurposed as spam traps.

    For very seasonal products or audiences that typically run on an annual cycle, expanding the window to 14 months may be safe with specific caveats. These recipients should be targeted sparingly, keeping the percentage of total volume below 5%. Ideally the content should be tailored to their seasonality and may include a reconfirmation option allowing them to choose whether to receive additional mailings. 

  • 14-18 months: Moving the engagement window to 18 months introduces additional risk, as these addresses have an even greater likelihood of being unused or repurposed. We generally advise against sending to these recipients.

  • 18+ months: In nearly all cases, we strongly advise against sending to recipients who have not engaged with an email in more than 18 months.

  • New signups: We recommend affording special treatment to those recipients who have signed up recently but never opened an email. We typically suggest a window of 30-60 days for new signups; those who do not engage within that period would be removed from the promotional mailing list. 


Re-engagement Methodology

For those recipients who have not engaged in an extended period of time, it’s common to run a re-engagement campaign designed to trigger their interaction with a message. In many cases senders undertake these campaigns only a couple of times a year, which can lead to deliverability issues triggered by sending to a large contingent of unengaged recipients at once.

By contrast, efforts to re-engage dormant recipients are typically more effective when done via small, ongoing campaigns instead of large one-off sends. Let’s look at an example of a brand who sends promotional emails twice per week to around 1 million recipients each time. We’ll assume those 1MM recipients have all shown email engagement within the past 9 months, but the brand also has some recipients who last engaged between 9-14 months ago that they’d like to re-engage.

WEEK 1 Engaged volume Unengaged volume Total volume
Send 1 1,000,000 50,000 1,050,000
Send 2 1,002,500 50,000 1,052,500
WEEK 2      
Send 1 1,005,000 50,000 1,055,000
Send 2  1,007,500 50,000 1,057,500
WEEK 3      
Send 1 1,010,000 50,000 1,060,000
Send 2 1,012,500 50,000 1,062,500

In this example, each send includes 50,000 different recipients who last engaged 9-14 months ago. Assuming 5% of those unengaged recipients record an open or a click, we see growth of 12,500 recipients onto the regular promotional list within a couple of weeks. Because the portion of volume being sent to unengaged recipients remains around or below 5%, the sender is able to recover unengaged recipients with minimal risk to their reputation or their overall deliverability. 


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