The past year has seen a reduction in spam complaints for email and strong deliverability rates, trends driven by the growth in mobile email opens ? especially on Apple devices, whose native email experience lacks a spam complaint feedback mechanism. However, if inbox providers suddenly begin accounting for this, any effect on deliverability rates could disappear. 

?Whatever influence that Apple devices are exerting over complaints and inbox placement is artificial, and whether the user experience is changed or mailbox providers begin accounting for it, or both, the resulting positive effect on deliverability can go away overnight,? said Tom Sather, senior director of research at Return Path. ?Or on Black Friday. 

Email deliverability slightly improved during the 2013 holidays period, and one reason is the growth of the iPhone and the lack of a "report spam" button in the native email clients. 

Marketers increasingly recognize the need for an email strategy that reaches customers with the best experience possible based on the device they are using. 

By sector, retail and financial services did the best at reaching customers? inboxes while publishers, media and entertainment providers trailed others industries. However, the results by sector were swayed by a number of large, global brands with very strong email marketing strategies while other companies in these sectors did not perform as well. 

Interestingly the Gmail Promotions tab appears to have not had the negative impact on email marketing that was predicted when it was first introduced in 2013. 

Return Path found that read rates for messages in the Promotions tab have approached 20 percent in 2014. Additionally, inbox placement rates are among the highest for any large mailbox provider. 

However, senders who asked subscribers to redirect promotional messages into their Primary tabs - which Google urged marketers not to do - have not seen the same success, with brands delivering messages to the Primary tab seeing much more mail diverted to the spam folder. This is because commercial mail in the Primary folder is being held to higher standard, with these messages ending up in the spam folder if subscriber behavior did not clearly indicate the message was wanted. 

For example, the placement rate was 1 percent for apparel marketers sending emails to the Primary tab on Gmail but 98 percent for emails sent to the Promotions tab. 

One takeaway from the introduction of Gmail?s tabs is that consumers like email marketing, as placing messages a click away from the Primary tab did not discourage engagement. Instead, it created the equivalent of a shopping folder, per Return Path. 

With Return Path reporting that other mailbox products are also adopting compartmentalized inboxes, marketers should keep in mind that messages qualify as inbox placed whether they are delivered to the Primary tab or Promotions. 

Further complicating how marketers define, measure and manage inbox placement is the proliferation of email applications. Return Path reports that a recent search of the iTunes store for email apps produced more than 16 million results. 

Also, mailbox providers continue to fine-tune their offerings to address consumers? changing needs. 

For example, Google is testing a grid-like view for the Promotions tab on Gmail that creates a Pinterest-like experience for users. 

More than simply delivering an image-driven experience, Grid View enables senders to optimize campaigns opens in real-time. 

?The surge in mobile email opens, especially on Apple devices, may have played a direct role in worldwide deliverability by reducing spam complaints,? he said. 

?This unintended consequence of the Apple mobile email experience may be helping marketers reach subscribers' inboxes. In the span of a year, email and mobile became inexorably linked.?