While the differences between Webmail properties such as Yahoo! Mail, Gmail, AOL and Hotmail may seem subtle, their user bases do not behave alike. A study of success metrics for marketing e-mails sent through MailChimp’s distribution service showed that Gmail users were most likely to open and click on e-mails.

Open rates varied from a low of just over 20% for e-mail sent to AOL users to a high over nearly 31% among Gmail users. The click rate on e-mails sent to Gmail accounts was more than 7.4%, compared with rates between 4% and 5% for Yahoo!, AOL and Hotmail users. Messages sent to Gmail accounts also had the lowest hard bounce rate, though other data indicates Gmail’s spam protection may be so stringent that messages disappear without producing a bounce.

A 2009 Return Path study, for example, found a 23% nondelivery rate for marketing messages sent to Gmail. According to comScore, Gmail is the third-most-popular e-mail property among US Internet users, though it posted the highest growth rate between July 2008 and July 2009.

Unique visitors to the service rose 46% to nearly 37 million. Yahoo! Mail and Windows Live Hotmail had significantly more visitors, at about 106 million and 47 million, respectively.

MailChimp suggests that demographic factors could be at work when it comes to the willingness of Gmail users to open and click on marketing e-mails, so the service’s continuing growth could bring its metrics closer to the average.

But for now, the user base may be particularly friendly to e-mail marketing.

Mobile internet may have taken time to find its footing with consumers, but now it is powering along, gaining users at a fast clip.

What’s more it has moved beyond just an occasional toy for a rapidly increasing group of people.

The number of people who access news and information on the internet on a daily basis more than doubled in the last year, rising to 22.4 million in January from 10.8 million in the same month in 2008, according to a new study from ComScore.

“It is now more than a novelty. It is something that is a utility,” says Mark Donovan, senior vice president for mobile at comScore.

The transformation for mobile stems directly from improved web technology and a dramatic improvement in content.

In many ways the change is similar to what happened with internet access via the PC some years ago. In the early days, when dial-up ruled and content was limited, people might surf a bit each month. It was still a novelty. It became a daily habit as more content became available and fast internet connections gained over dial-up.

“You saw how the computer became knitted into the fabric of their lives. That’s now happening with the mobile phone,” says Donovan.

Another factor is handsets that are handier for surfing, but as comScore points out, it’s not just smartphones like Apple’s iPhone. It found that 70 percent of people accessing mobile internet content were using phones with lesser features.

The big draw for mobile surfers is news and information. ComScore found that the number of mobile users who visited such sites on a daily basis has more than doubled, rising 107 percent, to 22.4 million, by January as compared the prior January.

But the fastest-growing category in terms of the number of daily users is social networks and blogs. The number accessing these sites was up 427 percent to 9.2 million.

The third-biggest category was financial services, trading stocks, and accessing bank accounts and the like. That was up 188 percent, to 3.2 million daily users. This is also a category that Donovan believes is likely to continue growing rapidly.

For advertisers the rapid shift to accessing the web via mobile phones makes this area far more appealing, says Donovan.

“We have shown that mobile is sizable audience, it is frequently used by 35 percent daily. Plus a big portion of those people are additive, in that advertiser wouldn’t get them by just advertising on the PC web,” he says.

He is referring to some previous comScore research that showed that light PC internet users are 30 percent more likely to be using the mobile internet. So mobile is a key way to reach them.

What’s more, the people who are surfing from their phones are a nice sweet spot for advertising, believes Donovan. They tend to be men ages 18-35, who are highly connected and highly distracted. The mobile phone is their connection to the digital world.

A Johnson Box is a part of a direct mail piece or letter that contains the key message, so named because it has been credited to direct marketer Frank Johnson.

Frank, a modest man apparently, claimed he did not actually create it, but only popularized its use.

Frank simply wanted to improve response to his offers for American Heritage magazine. He thought his box would capture the reader’s attention and entice them to read the whole letter.

Old Frank was right, and today most direct marketers employ the device. But as times changed, so did the technique of using the Johnson Box.

Today, you may find it in the middle or off to the side of the page or even down by the order form. In email blasts, the Johnson Box is the subject line.

So the next time you write a direct mail letter, add a Johnson Box. And the next time you read such a letter, see if it doesn’t jump right out at you.

P.S. Effective direct mail also includes a P.S., but that’s a whole ‘nother story.