A new deliverability study from Return Path Inc. claims leading Internet and e-mail service providers did not deliver 21 percent of permission-based e-mails to consumers' inboxes in the first half of this year.
This figure was down slightly from 22 percent of permission-based e-mails not delivered in the comparable first-half 2004 period, according to Return Path, New York. Though not meaningful as a trend, the increase in deliverability is attributed to better e-mailing practices and reputation.
ISPs and e-mail service providers using a host of filtering technologies to fight spam may be partly responsible for weeding out legitimate e-mail, Return Path said.
The study coincides with another deliverability report by Lyris Technologies, a Berkeley, CA, e-mail delivery firm. While delivery rates for permission-based e-mails rose for the third straight quarter, MSN's Hotmail and Google's Gmail filtered out more legitimate e-mails than previously, according to Lyris' quarterly deliverability report.
Lyris said that Hotmail's introduction of Sender ID in the recent quarter might have caused the spike in delivery problems to Hotmail. Sender ID causes Hotmail to deposit e-mail into bulk or junk folders when the sender cannot be verified.
Relatively new to e-mail, Gmail also may have delivery issues as it fine-tunes what gets through and what doesn't.
Gmail, MSN and Hotmail were fingered in Return Path's study, too. Gmail, along with Excite, blocked or filtered 39 percent of permission-based e-mail, MSN 33 percent and Hotmail 32 percent. EarthLink and USA.net shared a blocking rate of 10 percent while Mac.com was only 8 percent.
Return Path's study monitored a sample size of 140,000 marketing and transactional campaigns sent by clients using the company's Delivery Assurance Mailbox Monitor service from January through June. Return Path provides e-mail marketing services to these marketers.