Customers of Speednames, the subsidiary of domain name registration firm NetNames, have been unable to receive emails since yesterday.
On its status page the company said “it is currently not possible to receive emails at present.”
Outgoing messages are being sent successfully but it warned that incoming emails sent to customer accounts will not be delivered until the issue is resolved.
"Our engineers are working on this with the highest priority. We apologise for the inconvenience caused," it said.
Private equity private equity firm Hg Capital acquired NetNames for £153m in 2011. Last year the company brought in turnaround expert Steve Vaughan as non-exec chair to boost its fortunes.
In the last Companies House filing for the full year 2014, NetNames reported revenue of £50m and operating profits of £229,000.
The Register contacted Vaughan, but he did not wish to comment on Speednames' current email woes. ®