The UK's biggest broadband provider BT redirected its customers' outgoing emails to a single account for three hours on Tuesday.

The telco said the flooded inbox was an internal account it uses for test purposes and not a random unlucky subscriber. While BT did not provide details on the reason for the disruption, it appears to be the result of testing or maintenance gone awry.

"A small number of customers reported an issue sending emails earlier. Sorry about this, it's fixed now," BT said in a statement to El Reg.

"The mailbox in the delivery failure notification was for internal/test use and appeared in error, sorry for any confusion that caused."

Reg readers warned us earlier that their outgoing messages were getting forwarded to a mysterious stevewebb2@btinternet.com address that was bouncing email as the mailbox was full. There is a Steve Webb who works for Synchronoss Technologies, which – it just so happens – last month took over the running of BT's cloud services.

"My roles ... involve supporting email platforms for O2 and BT, looking after the mail gateway, the backend servers containing the mailboxes, calendars and address books and other servers in the platform," Webb wrote on his LinkedIn profile. "I have supported 28 million email accounts and 80 million emails per day."

Oh, looks to me as if #BT's SMTP email routing has gone horribly, horribly wrong this afternoon. — Jon Keen (@urzz1871) April 19, 2016

One tipster reports contacting BT support during the cockup and being told that "many" customers were experiencing the issue and that it could take as long as 24 hours to correct. BT told us the error was fixed at 3.30pm local time in the UK.

This is the second big outage to strike BT this year, though not as serious as the February router problem that knocked hundreds of thousands of users offline. ®