Microsoft said last week that eBay Inc. will soon drop support for its Passport service, originally intended to make the world's biggest software maker the gatekeeper of web identities.
But Microsoft said it will keep Passport up and running, despite the loss of one of its earliest and most important partners.
EBay said in a message to users that later this month it will stop allowing them to sign on to its web marketplace through Passport.
Passport allows users to store such things as passwords and credit card information for use across the web. With its launch in 1999, Microsoft aimed to insert itself in a key position in e-commerce transactions.
But the service has since fallen short of that goal due to several significant hurdles - including security and privacy concerns.
The move by eBay, far and away the most popular US shopping website, ends a partnership forged in 2001 and underscores consumers' unwillingness to embrace Passport outside Microsoft's own MSN Internet network.
"A very small percentage of eBay users regularly signed in using Passport," said eBay spokesman Hani Durzy, who added that the company also has provided alternatives to users who receive eBay alerts through Microsoft's .Net service.
Passport swiftly met with resistance on several fronts. The competitive response to Passport came in the form of the Liberty Alliance, a consortium of companies including Sun Microsystems, Hewlett-Packard, American Express and Sony. The group's aim was to create standards for identifying people on the web and to promote services to rival Passport.
Privacy groups and antitrust regulators weighed in with concerns, and in 2003 security experts unearthed a flaw that could have allowed scam artists to hijack older Passport accounts.
Retailers also balked at the prospect of having Microsoft at the center of online transactions and worried that it might one day try to take a cut.
Passport currently has 200 million users, many of whom use it to sign on to Microsoft's e-mail and instant messenger products.
The company continues to be committed to providing authentication services to its partners, a Microsoft spokeswoman said.