With millions of mobile workers commuting to and from the office each day and looking to remain productive while behind the wheel, software developers are tapping into the power of smartphone applications ("apps") that let you access e-mail, and in some cases, allow you to respond hands-free, too.

IncTechnology.com has written about hardware options for e-mailing while driving in the past, but downloadable software -- that won't break the bank and works with existing smartphones and carriers -- might be a preferred way to go for on-the-go businesspeople.

These apps rely on text-to-speech technology to read messages to you in a human-like voice, while replies are attached as an audio clip or transcribed back into text before sent.

Read your e-mails

iSpeech.Org's DriveSafe.ly, for example, can read your incoming e-mails and text messages to those running BlackBerry, iPhone, Android, or Windows Mobile devices. The sender also gets an automated reply to confirm the message has been received. The free version reads the first 25 words of the message, but upgrading to the Pro version ($30) gives you the first 500 words of a message, the choice of female or male voice, and other benefits.

Similarly, the free Text'nDrive app for BlackBerry or iPhone (and soon, Android) also allows you to listen to your incoming messages, but the Pro version ($10) also gives you the option to reply to messages with your voice. This app from Hands Free Software can automatically configure Gmail, Hotmail, AOL, and MobileMe user accounts, while those with other e-mail accounts might need to first input some info, such as POP or IMAP settings and SMTP settings.

Critics speak up

Carmi Levy, an independent technology analyst based in London, Ontario, says the safety factor is something businesses must consider before rolling out these apps to their employees. "While these new apps hold the promise of maintaining productivity while on the go, they ignore the basic fact that even hands-free communication at the wheel can be a dangerous proposition," says Levy. "Even if these apps free drivers from the illegal tyranny of texting with one hand and driving with the other, they nevertheless serve as a distraction by splitting the driver's focus between the road and his or her work."

Scott Steinberg, CEO and lead technology analyst for TechSavvy Global in Seattle, Wash., agrees with Levy. "Any distraction while on the road takes away from your concentration, but this is better than holding the phone up to your ear, which also may be illegal in your state, and certainly safer than texting or e-mailing while driving," says Steinberg.

Steinberg says while not perfect -- as they might pick up noise from the road -- these apps do a "pretty good job." "That said, hearing your e-mails is fine, but those send out replies will still need to double-check messages if they've been transcribed into text to ensure it's accurate," advises Steinberg.

Levy says these apps work as advertised for the most part, but as with many mobile solutions, some devices are better than others at supporting interactive voice sessions in a noisy vehicle. "If your particular phone's speakerphone capability is limited to begin with, these apps won't magically fix it," cautions Levy. "In many cases, Bluetooth headsets or in-car speakerphone solutions might improve the back-and-forth speech capability."

Network support is another issue, Levy says, as services which work flawlessly in an area with strong wireless coverage may fail miserably if you drive into a rural 3G dead zone.

Security and privacy concerns

Unlike DriveSafe.ly, Text'nDrive requires users to divulge their e-mail password, which might concern some.

"The security risk from sharing your e-mail password with a third party is no greater with these apps than with any other," believes Levy.

"It's common for us to share e-mail addresses for our Web-based accounts with a range of third-party apps and services -- this is no different, and as long as the company is legitimately trustworthy, users can proceed without concern that their passwords will be stolen and their accounts hacked," adds Levy.