Google?s unveiling of its Inbox mobile application and new tools for organizing email by precise categories will further give marketers an incentive to personalize their outreach to consumers in a world where one size no longer fits all.

Inbox allows emails to be grouped by precise categories, such as receipts or bank invoices while highlighting phone and package-tracking numbers and flight times. The move, which leverages the technology Google brought to Gmail last year permitting categorizing of emails from retailers or mailing lists, continues the Web portal company?s rethinking of email as most emails are open and read on mobile.

"Google is wisely giving consumers choice in everything from whether it even wants emails delivered in a new way to how they are grouped and categorized,? said Jeff Hasen, founder of mobile-strategy firm Gotta Mobilize, Seattle. ?Mobile users seek out products that make it easier to get to information they individually want, like a tracking number or business phone number.

"The customization aspect seems compelling,? he said. ?There's no more personal device than a mobile phone so one size doesn't fit all. This product will flourish or not depending on the awareness of it and the ease of setting it up and using it."

"Anything that gets users to more efficiently review emails should be good for marketers,? he said.

Inbox, which is still in the testing stage, also lets users set reminders and choose to have messages redelivered at a later time.

For marketers, the email landscape is becoming more complicated because of the proliferation of devices as well as inbox providers? efforts to better meet the needs of mobile users. 

The increasingly visual character of "Inbox by Gmail," as it was unveiled on Google?s official blog, is seen as a boon for mobile marketers.

?It's much easier to convey a message through imagery to an audience that is checking email in bursts on their phone throughout the day, meaning that visuals will play just as an important job in driving an action as copy is,? said Tom Sather, senior director of research, Return Path, New York.

The ability to hit snooze on a message for a later date may also prove to be useful for mobile marketers.  Users will be able to specify when they want to be reminded of messages, but will also receive help in determining when an email should be revisited. 

For promotional emails, this likely translates into Gmail looking for dates and times in emails, for instance when a sale starts or ends. The system will be intelligent enough to suggest when the user should be reminded of it. 

?Inbox by Gmail also has geofencing abilities in its to-do feature which I'd suspect mobile marketers could get creative with, by suggesting to-dos in their emails based on when the subscriber nears a brick-and-mortar location,? Mr. Sather said. 

Lastly, the revamp makes the tabbed inbox ? called Bundles ? more useful by adding categories for sorting emails that are essential for mobile users, such as purchase and travel, and giving users the ability to create their own custom bundles. 

?This should be a positive for marketers as it will allow their subscribers to focus in and engage with their email messages at the right time and right place,? Mr. Sather said.

By being able to combine data from channels like search and social with the inbox, marketers will be able to paint a complete picture of what people want and need before the individual even knows what he or she wants or needs. 

A recent Return Path report revealed that 17 percent of email marketing campaigns fail to reach consumers, going directly to junk folders, or disappearing altogether. 

Last year, Google changed the game for mobile email with a change to Gmail that made it harder for marketers to deliver dynamic content on mobile.

Until then, consumers had to opt to download images in an email, allowing marketers to track opens and views. With the change Gmail began caching all images on Google servers and changing inbox defaults to automatically download the images, causing some new obstacles for email tracking as well as adaptive email.

?Mobile is a major reason Google is revamping the inbox,? Mr. Sather said. ?Behaviors have changed and people are moving away from Web mail on desktops, but the current email experience on a phone is somewhat laborious. 

?Google recognizes that email is the center of people's lives, and also the workhorse of the marketing world, and I think it shows that we'll continue to see growth and innovation in email and email marketing, and just how powerful the data in our inbox is,? he said.