Most NHS email accounts are back online after a mass shutdown on Saturday that froze staff access to their accounts around the country.

HSJ has been told that the central NHSmail system was back online by 6pm on Saturday, with 95 per cent of accounts now accessible.

Earlier on Saturday, HSJ reported that emails had been inaccessible from about noon after what was described as a “complete shutdown” of the central service run by NHS Digital. 

Some users subsequently reported being unable to use email since 11 am and others said the service has been slow for several days. There are more than 1.2 million NHSmail accounts in England and Scotland, although some parts of the NHS run their own email system, which have been unaffected by the outage.

The source of the shutdown has yet to be confirmed and Accenture, which runs the system on behalf of NHS Digital, was urgently investigating on Saturday afternoon.

However, HSJ had been told that it may be linked to Accenture upgrading the data centre which hosts the email service last month. 

There is no evidence that the shutdown is the result of a malicious cyber attack, HSJ understands.

In a statement on its website on Saturday afternoon, NHS Digital described it as a “severity 1” incident.

“We’re really sorry to those of you who are affected and we’re working hard to get it fixed.”

NHS chief clinical information officer, Simon Eccles, confirmed the shutdown on Twitter on Saturday afternoon, describing it as ”exceptionally unusual”.

“NHSmail is completely down on all platforms. This is exceptionally unusual. The team and supplier are investigating.”

Accenture has been running the NHSmail system since 2016, after winning a £60m contract in 2015.