What's more, about a third of the Firefox users who were issued with the warning last week followed the link to update the Adobe software, said Mitchell Baker, the former CEO of Mozilla and current chairman of the Mozilla Foundation.
"This is a very high response rate," said Baker in a blog.
"A typical response rate for this [landing] page is around 5 percent."
Johnathan Nightingale, a member of Mozilla's security team, echoed this in an entry on the company's security blog. "Those results have been nothing short of awesome," he wrote.
On Thursday Adobe confirmed a spike in traffic to its Flash Player update page, and applauded Mozilla's move.
"For us, anything that others do to help users stay up to date is a good thing," said Brad Arkin, Adobe's director for product security and privacy. "We're glad to see Mozilla doing this."
'Your version of Flash can cause secruity issues'
After Firefox 3.0 and 3.5 users installed the security update Mozilla issued last Wednesday, they saw a message on the 'landing page' - the first page that appeared after the browser restarted - if they had an out-of-date version of Flash Player.
"You should update Adobe Flash right now," the message read. "Firefox is up to date, but your current version of Flash can cause security and stability issues. Please install the free update as soon as possible."
The message also included a link to Adobe's download site for the latest Flash Player plug-in.
On September 10, the first full day after the update rolled out, about six million users saw the landing page, said Ken Kovash, Mozilla's chief of metrics, in a blog. Kovash said more than three million were running an outdated copy of Flash, and of those, over one million clicked on the link to Adobe's download page.
"Beyond the total impact of 10 million clicks, the most impressive pattern that stands out is the click-through rate," said Kovash.
"While the Firefox 'whatsnew' page generally sees a click-through rate below 5 percent, the Flash update link alone has generated a click-through rate better than 30 percent. Phenomenal!"
Adobe's Arkin said that Mozilla's tactic isn't the first time a company's urged its users to update Flash. "Other sites, such as Facebook, have been doing this for awhile, and are already encouraging their users to stay up to date," Arkin said.
"No one has to ask our permission to do it."
Even though he welcomed Mozilla's plug-in check, Arkin said it isn't a complete solution to the problem of outdated software.
"Firefox's is a good approach for a certain demographic, but not all users have the rights to update on their own," said Arkin. "It's not the complete and final solution."
Arkin declined to go into specifics about what plans Adobe has in mind, or in the works, to boost update uptake.
See also: Firefox to roll out updates quicker