YAHOO Mail went down for several hours on Wednesday affecting thousands of users across Britain.
The outage appeared to hit most of the UK, with London and Manchester among the worst affected areas.
More than 900 people reported issues with the email service from around 6:00am GMT, according to the website DownDetector, which tracks online outages.
Some users said they had problems logging in, while others reported that emails weren’t reaching their inboxes.
A global map of reports filed to DownDetector suggested customers in the US were unaffected by the disruption.
Yahoo reported the issue, resolved by 11pm GMT on Wednesday, was the result of an error with a specific Internet Service Provider (ISP).
An ISP is a company that provides people with access to the Internet, such as Sky, BT or Virgin Media.
In a comment posted to Twitter, Yahoo did not name and shame the offending ISP.
“Some UK users are having problems logging into some services this morning,” the company wrote.
“On investigation, it seems that login issues for UK Yahoo Mail customers were limited to 1 ISP, and not related to any issues on our side.”
Email provider AOL Mail also experienced issues caused by an unnamed ISP on Wednesday. The problem was resolved by Wednesday evening.
On DownDetctor, users took to the comment section to vent their frustrations at the Yahoo outage.
“Unable to login online,” wrote one. “Tried downloading app but can’t log in there either. Guess it’s a login issue.”
Another fumed: “Pretty s**t when you are currently job searching due to redundancy to not have your email to check up on responses to applications etc!!!”
“The lack of communication from Yahoo about this is deafening! So disappointing,” one commenter seethed.
It’s not the only time Yahoo Mail has experienced problems in recent months.
Back in September, the service went down for several hours, affecting thousands of UK users.
Yahoo blamed a “technical issue” for the outage.