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An email chain has caused major disruption at the NHS after people started clicking “reply all” to a message sent to 1.2 million employees.

The blank message with the subject line “test” was inadvertently sent to the directory holding all NHS email addresses. According to The Register, as many as 80 people had hit “reply all” by 11.30am on Monday morning.


The service status page of the NHS IT support website shows major issues with internal NHS email and minor issues with all incoming and outgoing email. An incident report on the site explains that email delivery had been disrupted as a result of “several test emails” being “widely received by users”.

“This has been exacerbated by recipients replying in response and increasing the volume of emails associated with the list.” The deluge of emails has blocked some users out of their Outlook Web Access accounts, the status update continued.

NHS IT staff have removed the distribution list linked to the inadvertent reply-all chain, with associated spam emails also being deleted. An update posted at 1pm GMT explained the maintenance work was ongoing.