Talkspace, a New York City-based startup offering therapy sessions via the web and mobile devices, has raised $2.5 million. Spark Capital and Soft Bank Capital participated in the round, which was the company's first. In addition, AOL President of Video Ran Harnevo will join the company's board.

The startup is trying to address a perceived problem in the mental health field: because of various factors including time, expense, and social stigma, many people (between 60 and 70 percent) who could benefit from therapy don't get help. Talkspace is approaching the problem by offering unlimited chat and mobile messaging with a therapist, which provides a lower cost option than traditional therapy, can more easily be worked into busy schedules, and is potentially less stigmatized because users have the option to remain anonymous.

"Millions of Americans suffering with no access to help because of high cost and the stigma around therapy is a classic market failure situation -- it is a massive mismatch between the huge demand for help and the widely available supply of talented therapists," said co-founder and CEO Oren Frank in a statement. "The one-hour-a-week model just isn't enough anymore."

The site and the mobile app, which just launched last week on iOS, give a scaling range of options at different price points. For unlimited posting in therapist-led public forums, users pay $9 per week. For unlimited messaging, it's $25 per week. Finally, users can schedule a 30-minute video visit for $29.

Talkspace, formerly called Talktala, was founded in 2012. According to the company's press release, the service employs 40 therapists and reaches 50,000 patients. However, the company's Apple AppStore description says 200 therapists are on the app and it reaches 25,000 people. Talkspace didn't respond to a request for comment.

A few other startups are in the telemental health field, although they are more likely to focus on video visits than interaction through mobile messaging. AbilTo, which raised $6 million in March, identifies people at risk for mental health issues via their employer and reaches out with video visits. Breakthrough, an online video visit service, raised $5 million last July.