Email Blacklists Most Likely to Penalize Marketers During Holiday Shopping Season

New guide helps email marketers understand blacklists and avoid the junk folder

New York – June 3, 2014Return Path, the global leader in email intelligence, today released a new guide to help marketers understand email blacklists – lists of senders that are identified as sources of unwanted messages. Presented as an infographic, this guide illustrates findings from the analysis of 16 months of blacklisting events affecting large email senders, and includes insight into prominent email blacklists and how they influence inbox placement at specific mailbox providers.

For example Return Path found that London- and Geneva-based blacklist operator Spamhaus’ IP-based lists significantly influence inbox placement decisions at Gmail—moreso than at several other mailbox providers—potentially preventing more than half of blacklisted brands’ Gmail subscribers from receiving their messages. The guide specifically details the correlation between individual blacklists and senders’ ability to reach Gmail users’ inboxes. It can be found at

“Major blacklists can dramatically impact email performance, preventing senders’ messages from reaching subscribers, but even among marketing veterans many don’t clearly understand who operates blacklists or how they work,” said George Bilbrey, Return Path co-founder and president. “We especially wanted to illuminate the relationship between blacklists and Gmail inbox placement, which many marketers struggle to navigate.”

The holidays proved to be the most common time to land on a blacklist with more than 49 percent of blacklistings occurring in November to December. This may happen because holiday shopping represents such an important revenue opportunity for retailers, making marketers more inclined to adopt aggressive tactics to maximize audience reach. Blacklisting events are often associated with the introduction of new email lists from third-party sources, or with campaigns sent to long inactive subscribers. For brands that stay on blacklists for extended periods (one-quarter of blacklistings for one Spamhaus list lasted 7-8 days) the risk means losing contact with customers who may not buy again for 12 months.

Additional findings from the guide include:

  • Most important blacklists: by IP- vs. domain-based listings
  • Impact on Gmail inbox placement: by specific  blacklists
  • Average blacklisting duration: by specific  blacklists
  • Seasonality: times of year in which most blacklisting takes place
  • Peak days: days on which most blacklisting takes place
  • Peak regions: countries whose mailers are most frequently blacklisted


To conduct this study Return Path analyzed approximately 20,000 blacklisting events documented between January 2013 and December 2013. These events affected approximately 15,000 IP addresses used primarily by large consumer brands with established sender reputations. The following blacklists were included in this analysis: CBL, DNSBL, Invaluement, Return Path, Spam Cop, Spamhaus (PBL, XBL , SBL), and PSBL.

About Return Path

Return Path is the worldwide leader in email intelligence. We analyze more data about email than anyone else in the world and use that data to power products that ensure that only emails people want and expect reach the inbox. Our industry-leading email intelligence solutions utilize the world’s most comprehensive set of data to maximize the performance and accountability of email, build trust across the entire email ecosystem and protect users from spam and other abuse. We help businesses build better relationships with their customers and improve their email ROI; and we help ISPs and other mailbox providers enhance network performance and drive customer retention. Information about Return Path can be found at


Peter Girard
Return Path
+1 646 367 3923
[email protected]

Mollie Leiser
Weber Shandwick for Return Path
+1 212 445 8142
[email protected]


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