The firm has not been hacked, but it appears that the group admin sent out a round-robin developer email, but used the CC option instead of the BCC (blind CC) facility in email.
The result was a tidal wave of anger from the beta test users, many of whom are software developers themselves.
"@DolphinBrowser just got an email from donotreply@dolphin-browser.com with hundreds of email addresses and some other hash codes :S," said one Twitter user.
In an official apology posted to the web yesterday afternoon, Dolphin said that the error was down to the use of a different email service to the one the firm typically uses.
"Through an unfortunate error by one of our employees, some recipients were able to see the email addresses of others who are also our beta testers. Needless to say, it was never our intention to reveal this information and for that we are genuinely sorry", said the company.
"Those who support our product and give us valuable feedback expect and deserve to have their personal information protected. In this case, we failed to do so and we will ensure it will not happen again in the future", the firm added.
Reporting on the email security faux pas, the Softpedia newswire said that emailing errors are not a rare occurrence and have happened to larger companies.
"Back in December, a Telstra employee accidentally exposed the personal details of 570 customers by sending them to the wrong mailing list", notes the newswire.
"In November, a Seton Hall University employee sent an Excel spreadsheet containing the personal and educational information of 1,500 seniors to 400 other students", it adds.
"Finally, in January, former Apprentice candidate Alex Epstein exposed the email addresses of hundreds of journalists, editors and other media representatives in UK after failing to use BCC when sending a job seeking email."