Yahoo Mail users across the world are unable to access their emails after the site crashed.
Reports of problems began just after 7am on Thursday, as customers took to social media to say they were unable to log-in or read their mail.
According to Downdectector.co.uk, thousands of people were still complaining as of 11am about a massive outage to Yahoo Mail services, especially in the UK and US.
In a statement on twitter, Yahoo Customer Care said: "You may not be able to access some of our services, including email.
"Our top priority right now is getting this fixed. We appreciate your patience."
"We understand how difficult this must be for you. We are working especially hard to fix this. Please stay tuned for updates," they added.
A couple of hours later just before 11am, Yahoo updated customers to say: "We will try our best to keep you in the loop and will be posting as soon as it is fixed".\
Twitter users were asking the tech giant what the problem was and how long the site would be down for.
Others said when they tried to log on, they either got the message: "Unknown Host" or "Will be right back.... Thank you for your patience. Our engineers are working to resolve the issue."
Stephen J Sweeney: "Yahoo! Mail! Is! That's! No! Fun!" while Florie Lhuillier said: "Not been able to log into my account for the past couple of hours, what's going on @Yahoo?"
Starfraz Manzoor said: "This is not a good day to be one of those old schoolers who has stayed with Yahoo Mail."
Another Twitter user called Shelly joked about replying to emails, saying: "Yahoo Mail server is down - guess that means I can postpone catching up on my emails and blame Yahoo (I obviously had every intention of responding to email today, obviouslyyy)"
A spokesperson from Verizon Media representing Yahoo said: “We are aware of a technical issue that is impacting our services.
"We’ve been able to get some services back online already and appreciate our customers’ patience as we work to get everything up and running as soon as possible.”
PUKmedia \ Evening Standard