YouSendIt, a Mountain View, Calif. service that lets professionals deliver large files over the Internet, said it has raised $10 million in a second round of venture capital financing.

The funding comes at a time when dozens of companies are helping speed up the delivery of files in multiple ways. “There are a zillion of them,” said Nick Sturiale, an investor with Seven Rosen Funds, which provided the funding, along with Sigma Partners, which led the round, and Alloy Ventures.

However, most services are not focusing purely on file delivery — many of them are offering a service for free, as part of a large range of services. YouSendIt’s niche: Helping small businesses and independent professionals send large data files — for example, design or music files — for a monthly subscription. Subscribers pay between $5 and $30 monthly, depending on the services they want. YouSendIt has built in things such as security features, as well as an authentication service, to make sure senders know that recipients have received files. This way, it hopes to differentiate itself from other services focused on consumers, such as Pando. Unlike YouSendIt, Pando uses peer-to-peer technology.

Such services are needed, Sturiale said, because professionals wanting to send large files are constrained by data limits imposed by their Web mail accounts. They’re also more convenient than downloading files onto a CD and shipping, or using FTP servers.

YouSendIt said it has four million registered users.