Best practices for list hygiene

List hygiene is an important factor that impacts your sending reputation. Mailbox providers place email in the spam folder or block email from senders who do not adhere to good list hygiene practices.

Symptoms of poor list hygiene include blacklistings, spam trap hits, high complaint rates, and high unknown user rates. 

Where to get supporting data

The following data sources can help you evaluate your list hygiene:

  • Return Path's Real-time Email Validation
  • Return Path Platform
  • Return Path's Certification program
  • Microsoft's Smart Network Data Services (SNDS)
  • Delivery Log Analysis (DLA)

Best practice recommendations

  • Sign up for all available feedback loops and promptly remove subscribers who complain.
  • Remove unknown user addresses after the first bounce.
  • Reject malformed addresses such as at all points of collection.
  • Remove malformed email addresses from your list file; such as or
  • Prohibit the use of role accounts such as postmaster@, abuse@, or sales@ to sign up for your email program.
  • Consider using a list cleaning service to help identify invalid email addresses.
  • Implement a strategy for identifying and segmenting inactive subscribers. This can include changing the frequency you send to your inactive subscribers, sending them a win-back campaign, or, if necessary, removing them from your list entirely.
  • Ensure subscribers are able to update their email address, either through a preference center or Email Change of Address (ECOA) service.
  • Offer a global unsubscribe option and allow subscribers to unsubscribe from specific email streams via a preference center. 
  • Ensure addresses are segmented or flagged by source if you obtain email addresses from a third party. This can help you identify sources of invalid and risky email addresses.
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