A Microsoft executive late Thursday used the furor over Mozilla's decision to curtail support for Firefox 4 to plead the case for Internet Explorer in the enterprise.

"I think I speak for everyone on the IE team when I say we'd like the opportunity to win back your business," said Ari Bixhorn, director of IE at Microsoft, in a post on his personal blog. "We've got a great solution for corporate customers with both IE8 and IE9, and believe we could help you address the challenges you're currently facing."

Bixhorn addressed his open letter to John Walicki, the manager of workplace and mobility in the office of IBM's CIO. Earlier Thursday, Walicki and others had voiced their displeasure with Mozilla's decision to retire Firefox 4 from security support when it launched the new Firefox 5 this week.

In a comment appended to a blog maintained by Michael Kaply, a consultant who specializes in customizing Firefox, Walicki called Mozilla's decision to end security support for Firefox 4 a "kick in the stomach."

Walicki said his company has 500,000 corporate users on Firefox -- a year ago IBM set the open-source browser as the default on all new PCs assigned to workers -- and complained that IBM had just completed testing Firefox 4 and was planning to roll it out later this year as a replacement for Firefox 3.6.

"I'm now in the terrible position of choosing to deploy a Firefox 4 release with potentially unpatched vulnerabilities, reset the test cycle for thousands of internal apps to validate Firefox 5 or stay on a patched Firefox 3.6.x," Walicki wrote.

Bixhorn was quick to exploit the opportunity.

"Although I'm in no position to question a competitor's approach to customer engagement and support, I did want to take the opportunity to clarify the Internet Explorer team's commitment to, and support for, our corporate customers," said Bixhorn, who then spelled out Microsoft's position.

"Enterprises have always been, and will always be, an important focus of ours," Bixhorn said.

He also reminded Walicki of Microsoft's long-standing policy to support each edition of IE "as long as the latest version of Windows that it runs on is supported."

That means, Bixhorn continued, Microsoft will support IE9, which launched a week before Firefox 4, through January 2020.

Mozilla pulled the support plug on Firefox 4 three months after its late March debut.

Asa Dotzler, director of Firefox, has made it clear he doesn't consider enterprise users worth supporting.

In several comments added to a follow-up post by Kaply, Dotzler did not mince words.

"Enterprise has never been (and I'll argue, shouldn't be) a focus of ours," Dotzler said. "I can't imagine why we'd focus at all on the kinds of environments you care so much about."

Later Thursday, Dotzler essentially said it was a return-on-investment decision.

"Years ago, we didn't have the resources [to solve the enterprise support problem]. Today, I argue, we shouldn't care even if we do have the resources because of the cost benefit trade," Dotzler said. "A minute spent making a corporate user happy can better be spent making many regular users happy. I'd much rather Mozilla spend its limited resources looking out for the billions of users that don't have enterprise support systems already taking care of them."

Near day's end, he was even more blunt: "I'm basically saying that I don't care about making Firefox enterprise-friendly," Dotzler said.

Some commenters weren't sure how to take his comments.

"Sorry Asa ... I seriously do not know if this is a joke or if you honestly think that the world loves FF [Firefox] that much," said a commenter identified only as "Eric."

But Bixhorn seemed certain that Mozilla's message was coming through loud and clear.

"And John [Walicki], as you point out, Mozilla's recent decision to accelerate the pace of their releases further accentuates the problem of only supporting the latest version of Firefox," said Bixhorn.

"Let me know if you'd like to discuss this further," he concluded, and published his email address.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His email address is gkeizer@ix.netcom.com.