Mozilla is planning to shunt 12 million users, who are still surfing the web on its aged Firefox 3.5 browser, over to a more recent version.
"We need a plan to obsolete [sic] Firefox 3.5 as we can't support it into perpetuity," said Mozilla.
"We have been frustrated with our efforts to move users off of old releases and are worried too many people do not upgrade and are on vulnerable and unsupported versions of Firefox."
Ideally the open source outfit wants to see all its users upgrade to the current version of its browser - Firefox 4.0.1. However, many people still connect to the internet via computers that were released in the pre-iPad age.
Besides from that, Mozilla has committed to continuing to support Firefox 3.6, allowing older machines, such as Power PC Macs, to be able to connect to the interwebulator via that version of the browser.
To get the message across to Firefox 3.5 holdouts, Mozilla plans to issue a warning to all such users telling them they are running an out-of-date browser that is no longer supported against the threat of online attacks.
The message will be displayed through Google's default search page starting tomorrow.
"At the same time we also put a big warning on all Mozilla web properties, pointing them [users] to the new version to download," it said.
Anyone with automatic updates switched on will have Firefox 3.6.18 pushed out to them on 21 June, the same day Firefox 5 is expected to be released.
Mozilla released Firefox 3.5 in June 2009 six months later than scheduled. ®