Two Cambridge entrepreneurs launched their first software product this week to provide users with reports on their e-mailing habits — a crowded market with a large growth trajectory, particularly among enterprise IT departments looking to reduce wasted time.

Xobni Corp., taken from the words “in box” spelled backward and pronounced “zob-nee,” is offering its program free for personal users and plans to launch a business version within two months, said co-founders Adam Smith, 21, and Matt Brezina, 25.

The idea behind the software is to save businesses — Xobni’s eventual target market — money by identifying inefficient e-mailing practices. They consider the software an e-mail productivity tool.