More deliverability data

Last month, we talked about some data on deliverability of legitimate bulk email to various public email services, in this post. Today, we have some additional data to share. Here are some highlights and analysis:

During the first three months of 2005, 4% of legitimate bulk email tracked by Lyris's Email Advisor service was caught in quarantines (or "bulk folders"). An additional 6% was rejected outright, or silently discarded. In other words, only 90% of this requested email mail actually arrived in the users' inboxes.

According to Lyris, the best spam filters for delivery include SpamCop, CompuServe,, and Tiscali. Bottom of the table are Concentric, Google Mail, SBC, and Yahoo!. The full report is here [pdf].

As we've said before, here, here, and here, the "deliverability" problem is a significant collateral damage issue in the fight against spam. Anti-spam vendors'  methods of measuring false positives are extremely suspect, as they rely on all end users diligently reporting all false positives, which they almost never do. The quoted figures are typically in the 0.01-0.1% range, and often deliberately ignore newsletters, opt-in marketing, and other legitimate bulk email. Customers' actual experiences tend to be in the 0.1-1% range.

Note that these quoted percentages are as a proportion of all mail, including spam, not just of legitimate mail. That will also make them look much smaller than they actually are. Vendors sometimes even try to concentrate on something called "false criticals," as if requested email content is somehow unimportant to recipients.

How can direct marketers get their messages through more reliably? We wrote about this problem before. See here.

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