In the final quarter of 2012, close to 100% of marketing emails sent to Optus and Dodo mailboxes failed to reach end-users inboxes, a new study into email performance in Australia has found.

For the whole of calendar 2012, only 57% of marketing emails sent to Optus inboxes, which represents between 6%-7% of all Australian mail accounts, were successfully delivered, with the remainder being sent to spam filters or blocked.

Optus and Dodo were not alone in their spam filtering woes, however, with close to one in five emails sent to Australian inboxes failing to reach inboxes. The study was conducted by international email intelligence firm Return Path.

Optus declined to comment on the report specifically, but a spokesperson said that the company's placement of marketing emails into spam folders was a result of customer demands.

While some of the blame can be attributed to email providers with overly zealous spam filters, poor email list management practices by Australian marketers was also evident, Return Path’s CEO Matt Blumberg told B&T.

Best-in-class marketers easily achieve spam complaint rates of less than .1%, zero spam traps and unknown user rates of less than 1%. Current rates in Australia are .4% of complaints from an IP address that users mark as spam and 3% of emails sent from an IP address to unknown addresses. These higher than global standards gave Australian marketers a collective sender’s reputation score of 74%. Return Path says that reputation is responsible for 83% of delivery issues.

In an industry by industry breakdown covering 500 Australian brands, the education sector fared the worst with a staggering 81% of emails delivered to spam and only 4% of emails being read. The best industry was the utlities sector, with a read rate of 57% and a spam rate of 1%.

The study also found that Australian subscribers continue to open more of their email from mobile devices, underscoring the need for marketers to implement a mobile email strategy. Between October 2010 and October 2012, the use of mobile devices to check emails grew 300% to surpass the number of emails checked via webmail.

Interestingly, the study also found that in Australia, iPhones represented 49% of mobile devices used to check emails. What was also clear, was that people are using various devices throughout the day to check emails.

Conducted by international email intelligence firm Return Path, the study tracked the delivery, blocking and filtering rates for campaigns that used the Inbox Monitor seed list system; this study also tracked the read rate, spam folder placement rate, and messages deleted without reading rate using subscriber panelists at Gmail and Yahoo!; for reputation metrics, this study used data received from global mailbox providers participating in the Return Path Reputation Network to measure the complaint rate, unknown user rate and average number of spam traps; Return Path reviewed data from six ISPs in Australia, two ISPs in New Zealand, and two worldwide providers: Gmail and Yahoo! for placement and engagement benchmarks. Return Path also reviewed reputation data received from more than 80 global mailbox providers.

The complete study, including infographics, can be downloaded here.