Improving Email Delivery

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Today I attended a webinar hosted by SenderScore on topic of email deliverability.  It was a good overview (and reminder) of the state of delivery and what tactics and strategies can be used to improve email deliver results. Most of this is not new information but I thought I would add and expand upon my notes since it is a nice review:


I. Statistics

  • North America Delivery – Approximately 81% of email is making it to the email inbox; 19% is either falling into spam boxes or undelivered. This is the best in the World currently.
  • China Delivery – The rate is the lowest with 58%, due to the ‘great spam wall of China’.  It has been noted that non-chinese language emails have a much lower delivery rate than native Chinese.  And for marketers, unfortunately the spam wall guidelines require that you use “ad:” at the beginning of your subject line, which apparently they’re automatically disregarding those emails.  So delivery is very tough here.
  • Steady Future – Delivery rates have leveled off in recent years, after several years of significant.  So barring any major government policy changes (China) the rates should remain steady in the near term.

II. Strategies (for marketers)

  • Control List Acquisition – Perhaps the first and most obvious line of defense.  They used as an example of how they manage their affiliate partnerships and wrangle them through the landing page that they control.  This gives them the opportunity to control and filter what actually ends up on their list, which they do.
  • Make it Easy to Unsubscribe – If a user doesn’t want to be there, they’re going to become unresponsive to emails anyway, and there’s a good chance they’ll just click the spam button rather than the unsubscribe link.  A recent study found that 47% do exactly that.  So you’re better off making it easy for them to leave if they want.  Consider placing the unsubscribe link at the top of the email instead of in the footer.  Some ESPs are even considering requiring this in the future.
  • Set Expectations – It is good to be clear about what users are signing up for in your call to action for signup, and to further iterate what they’ll receive, when, from what email, address etc with our initial welcome email.  Setting these expectations will help them to lower their guard.  You can even ask them to whitelist you in the beginning.
  • Don’t Overuse Old Emails – It has been found that potency of an email address falls of significantly after the first couple weeks. The likelihood of getting marked as spam meanwhile increases at a similar rate.  Its best to retire inactive emails after 6 months and only ping them with periodic emails to confirm if they still want to receive emails from you.  And if after a few attempts there is no response, drop them completely.

III. Tactics

  • Feedback Loops – you can signup for feedback loops with all of the major Email Service Providers (ESPs) to get responses back on the failed emails, rejections, blocks, etc.  This can provide visibility to correct major issues.
  • Keep List Clean – If possible, scrub incoming emails before committing them to your list.  Correct common type-os and mispells (such as hotmaol) and remove obvious fake email addresses (such as  Also avoid sending to so-called ‘role’ accounts such as admin@, info@, contact@, etc.  This can be done algorithmically with a little code, or there are 3rd party services that offer plugins for this as well.  This will help to keep hard bounce rates down.
  • Seed Lists – Keep a couple of test accounts with each of the major ESPs and a couple randomly selected small ESPs.  Periodically check these to see how delivery is going, are you landing in the spam box? is doing this and found it to be an excellent diagnostic tool.
  • Monitor Sender Score – Monitor your score on They offer a free tool to indicate your reputation with the ESPs, on a 1-100 scale.  88 is the threshold for a generally good score and for which you likely will not have any difficult.
  • Remove Bounces – Diligently remove hard bounces, you don’t want to have more than one hard bounce to the same email address; that’s either a flat out rejection or a fake email address and will really impact your reputation score.  Also, remove soft bounces after 5 bounces.  Soft bounces are less serious issues such as a full inbox or a “Im on vacation” auto-reponse.
  • IP Blacklist Monitoring – Periodically check for IP black listing at places such as Spamhaus and MXToolbox.  Any issues with your IP being blacklisted will surely negatively impact your reputation score.
  • Use Static IP Address – It is very important to make sure you’re on a static IP address and don’t change that address too often.  Spammers have notoriously cycled their IP addresses periodically as they develop a bad reputation score. To avoid being flagged for suspicious IP behavior, keep with the same IP address.
  • Spam Traps – Perhaps the worst of all, avoid spam traps.  The ESPs have intentionally recycled old email address and created other trap emails and put them on to websites to try to catch people buying old lists and scraping websites to create lists.  Hitting even one spam trap can have a significantly negative impact on your reputation score, so you want to avoid introduction of any such emails to your list.