With the holidays upon us, it’s a good time to revisit the importance of good list hygiene in driving ROI and reducing costly ISP blocks. Senders who focus on list quality over list quantity during the holiday season are consistently rewarded with higher engagement rates and fewer sending problems.

Engaged segment

To increase the size of an engaged segment:

  • Build an automated re-engagement strategy for subscribers who have not opened a message in the past 6-12 months.


Sending performance

To improve sending performance for an engaged audience:

  • If possible, segment lists based on level of engagement: highly engaged, moderately engaged, and less engaged. Skip unengaged. Send to the most engaged segments first to reduce the risk of less-engaged subscriber problems affecting deliverability to more engaged subscribers. Less-engaged subscribers carry a higher risk of marking a message as spam, having full inboxes, or becoming abandoned accounts that an ISP may convert to a spam trap. Remove addresses that are not properly formatted (e.g., “fdfdsd[at]34dsds[at]ssd”).
  • Schedule mailings with more than enough time to complete before the subscriber is expected to take action.



To reduce the risk of ISP blocking:

  • Remove addresses that have previously hard bounced.
  • Remove addresses that soft bounce 3 times or more, and consider removing “mailbox full” bounces after the first occurrence.
  • Remove "role account" addresses (e.g., info@, postmaster@, abuse@, support@, techsupport@).
  • Consider using a double opt-in mechanism when possible to confirm subscriptions ahead of holiday campaigns. Relying on a double opt-in approach greatly reduces the risk of sending to unknown mailboxes or to recipients who didn’t request your message.
  • Know your complainers (and don’t send to them!). Keep track of complaint addresses received through ISP Feedback Loops. When adding new opt-ins to the list, exclude these complainers by either purging them from the list upstream or suppressing them at send time.
  • Remove inactive subscribers. If they haven’t opened for a long time, let them go! Disengaged or abandoned addresses carry a higher risk of becoming spam traps, and ending to spam traps increases the risk of an ISP block.
  • Provide subscription management options to your subscribers:
    • Give subscribers an easy way to opt out of the current communication, or all communications. Many subscribers will choose to mark a message as spam if it takes more than 2 seconds for them to opt out.
    • Give subscribers an easy option to opt down. Subscribers may want to reduce their volume or cadence of communication, not necessarily eliminate it entirely.
    • Implement a Preference Center to give subscribers more control over which communications they receive – they may simply prefer a different communication.
    • Honor ALL opt-out requests, not just those received through a Preference Center or unsub link. Opt-outs received via email or through a call center should also be removed.


Contact our team or reach out to your Selligent Relationship Manager with questions or for help implementing any of these best practices recommendations.

Happy Holidays!

Looking for some ways to better leverage email? Check out our whitepaper on designing and sending email.

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