Yahoo is removing its recently introduced security and anti-spam features after identifying them ass the cause of problems experienced by users trying to collect POP email from external accounts.

The problem arose after Yahoo added Secure Sockets Layer (SSL) capabilities to Yahoo Mail's POP mail function and beefing up its spam filters. However, Yahoo has run into problems solving the issue and has instead decided to remove the new security features for now until the problem can be resolved completely.

Yahoo Mail is a company crown jewel and a key piece of its ambitious plans to boost advertising, increase traffic, attract more developers and better compete by giving its users a 'social profile' dashboard to unify and manage their Yahoo services.

A week-long, ultimately unresolved problem affecting Yahoo Mail users hampers the turnaround effort and comes at a bad time, particularly with the upheaval around Microsoft's acquisition offer and a looming shareholder proxy fight to oust current board members.

The rollback of the SSL and anti-spam features is under way and will take "a few days" to reach all users, Ryan Knight, Yahoo Mail Community Manager said, in a blog.

"What this means is that your ability to retrieve from these accounts should be completely restored, however it also means that we will be rolling back the recently added option to use SSL. If you have added an account that requires SSL, retrieval from that account will no longer be possible," Knight added.

One Yahoo Mail user, Mike Bradley, thinks Yahoo waited too long to pull the new features and could have done a better job communicating updates about the situation.

"As soon as there were reports of problems, they should have rolled back immediately instead of waiting a week. Also, they should have updated the blog more frequently," he said. "The most frustrating thing is to not know what's happening, and frequently updated communication could have made for a better interaction with those of us affected."

Bradley, who uses Yahoo Mail both for work and personal communications, first noticed the POP problems last Wednesday. "'Server busy' error messages lasted two days, then I started getting time out messages for two days, then I started to get mail slowly, but not all my mail," Bradley explained.

He noticed that not all messages were making it to his Yahoo account because he also gets his email on his mobile phone. "That's still happening today, and this morning I got the 'server busy' pop-up error message again. It's slowly coming back to life but when I retrieve email, nothing appears in my inbox for 5-10 minutes after the 'checking e-mail' message disappears," said Bradley, an otherwise satisfied Yahoo Mail user since 1995.

Knight first acknowledged the problem in the Yahoo Mail blog on June 3, when he informed users that the company's engineers were already rolling out a fix.

The problem persisted, however, and on June 6 Knight said that, despite the fix, outstanding issues remained and that Yahoo would continue seeking a solution.

He also explained the new features whose rollout led to the problems: "Recently we made some changes to how external account retrieval works. Most notably we added SSL functionality (enhanced security technology), which many users have been clamoring for. We are also taking steps to improve spam blocking for messages that are being retrieved from these external accounts, by running them through more aggressive filters. Unfortunately we encountered some unexpected problems that lead to server errors or processes timing out for some users," he said.

A Yahoo spokeswoman Kelley Podboy confirmed that the most recent blog from Knight contained the most up-to-date information available about the issue. "We are also sending direct email to all users who have recently enabled SSL external accounts to notify them of the change," Podboy said.

Yahoo Mail has two POP-related services, according to Podboy. One is 'POP in' a free service for retrieving messages from external accounts, which is the one affected. Another is 'POP out' for downloading messages using a desktop email application, such as Outlook, and accessing them offline. The latter service is unaffected by the problem and available as a premium feature to Yahoo Mail users who pay $19.99 (£10) per year for the service's 'Plus' plan, she said. Both services are available to users of Yahoo Mail Classic and the New Yahoo Mail.

Another web giant has faced technical problems recently. Amazon's main site had availability and performance problems at the end of last week.