Self Debugging Email Deliverability Issues

The below listed points help you to self-debug email deliverability problems.

  • Check if all the compliance requirements are met. Expected results are:
    • SPF, DKIM, DMARC pass

    • DMARC policy [p=reject]

    • List-Unsubscribe header

    • In-body unsubscribe link

  • Check if the email setup is intact.
  • Look for any volume spikes. Expected results are:
    • Consistent volume pattern while looking at week-by-week summary.
    • No unusual volume spike (more than 1x growth compared to the highest volume in the last 30 days) in any day.
    • Less than 10 10-day gap between (high volume) sends.
    • Less than 3 weeks gap in between high volume sends
    • Ramp-up should be as per the plan, if in the ramp-up phase.
  • Look for any unusual target segment such as inactive users targeting, missing suppressions, or the presence of unusual emails in the list. Expected results are:
    • Optimal active v/s inactive targeting: 70:30.
    • Proper suppressions and frequency capping exclusions.
    • No inactive users (6+ months) in the usual target segment.
  • Check if there has been any suspicious sign-up. For example, a sudden spike in welcome campaign volume would be suspicious. Unless there is an activity going on or it’s the peak sale season, there should not be a more than +- 20% difference in the usual welcome campaign volume. Expected results are:
    • No unusual sign-up activity
    • No bot signups
    • No unusual app/site activity
  • Check postmaster data for reputation at Gmail; check SNDS for IP status at Microsoft. Expected results are:
    • HIGH reputation at Gmail
    • Less than 0.1 % of users reported spam on Gmail
    • Green-filtered results at SNDS
  • Check the performance metrics for the last 15 days, weekly performance going back 90 days, and monthly performance going back 6 months. Expected results are:
    • More than 99% delivered rate, except for the Welcome campaign or double opt-in campaign.
    • More than 30% unique open rates. Consistent through weeks for each segment group - active, inactive, personalized, triggered, etc.
    • Stable click rate - consistent through weeks for each segment group - active, inactive, personalized, triggered, etc.
    • Low complaint rates (<0.1%)
    • Low unsubscribe rates (<0.5%)
    • Consistent conversion rates from week to week for each campaign or segment group.
    • Consistent performance for each triggered campaign or flow campaign.
    • No deferrals.
  • Read all the failure reasons to see if there were any blocks due to IPs/domains being in block lists or due to low reputation. Expected results are:
    • No soft bounces due to IP/domain blocks or mailbox provider blocks.
  • Check the HTML content. Expected results are:
    • No personalization failures
    • No distorted or poorly formatted emails
    • No spam-like content
    • Personalized or segmented for each send
    • Light images or videos that load quickly
    • Consistent branding in emails.

After you spot the issues, go into the repair mode, then slowly test and resume sending smaller volumes to the most engaged users at a low RPM and then ramp up.


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