Yahoo Mail outage blamed on "hardware problems"
Thousands of users still locked out of their accounts
Yahoo has blamed ongoing webmail problems on "complex" issues with its data centres, saying they were "harder to fix" than anticipated.
Yahoo Mail has been down for some users worldwide since Monday night, though reports suggest there have been problems delivering email since 25 November.
Yahoo only acknowledged the problems this week and said it was working "round the clock" to fix the problems. But some users are still unable to log in, Yahoo Mail chief Jeff Bonforte admitted.
According to Bonforte, "a couple of thousand users" are still locked out of their accounts. He described the outage as "awful" and admitted that Yahoo was struggling to clear emails sent between 25 November and 9 December.
"We have hundreds of millions of messages to deliver," Bonforte told one customer via Twitter. "Customers will see varied delivery times for [a] number of hours."
Yahoo said it had managed to deliver about a third of emails sent during the outage, with the remainder expected to clear by this afternoon in the US. That means any British users having trouble sending or receiving emails might not see an updated inbox until tomorrow morning.
The outage is particularly embarrassing for Yahoo, given Bonforte sent an internal memo to Yahoo employees just three weeks ago asking them to switch from Outlook to Yahoo Mail.
"Earlier this year we asked you to move to Yahoo Mail for your corporate email account," reads the memo, written by Bonforte and CIO Randy Roumillat. "25% of you made the switch (thank you). But even if we used the most generous of grading curves (say, the one from organic chemistry), we have clearly failed in our goal to move our co-workers to Yahoo Mail."
It appears the remaining 75% largely prefer Microsoft's Outlook, something the pair described as an "anachronism of the now defunct 90s PC era".