While commercial e-mailers who apply so-called best practices to their efforts get significantly higher-than-average delivery rates, seemingly small infractions can cause serious damage to an e-mail program, according to a recent study by deliverability concern Return Path.
Commercial e-mail servers studied by Return Path achieved average delivery rates of 88%, with 9% rejected and 0.71% filtered, the company reported.
This is compared to 56% delivered, 20% rejected and 8% filtered for legitimate servers overall.
“But it’s important to note that seemingly small infractions can doom an e-mail program to junk-folder purgatory, or worse, send it to the black hole we all call ‘missing,’” said Return Path’s analysis of the study.
The company found that so-called legitimate servers with even one spam-trap hit saw their delivery rates plummet to 38% on average, and IPs that were listed on just one of the top 12 blacklists saw their delivery rates plunge to an average of 35%.
Also, mailers with unknown-user rates—the percentage of e-mail sent to non-existent addresses—of below 10% achieved 67% deliverability rates on average, while those with unknown-user rates of 10% or higher achieved average delivery rates of 44%.
Meanwhile, the study found that the vast majority of e-mail is spam, phishing attacks and other scams.
For example, 46% of e-mail traffic comes from hosts “which should not be sending mail at all,” such as compromised hosts, dynamic IPs and a variety of other “non-mail servers,” the study determined.
Another 34% of e-mail comes from servers that are difficult to classify, according to Return Path. “Either they are not legitimate mail servers or they are mail servers with enough problems that leave them in the unknown category due to their behavior,” the study said.
As a result, just 20% of e-mail comes from legitimate servers, or servers that are “real, static” and “well configured,” reported Return Path.
“The e-mail universe is a big, ugly, scary place,” said the study. “The volume of e-mail sent every day is overwhelming and most of it is spam.”
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