Computer Weekly has seen an email from the ISP’s technical support department revealing the action, but it gives no reason for the block.
“Yahoo and BT have blocked a very, very large number of IP addresses of UK2,” it read. “This has indeed been escalated to beyond critical as this is a very extreme issue.”
The problem began on 19 September, meaning users have been missing out on emails for over a week.
“The reason it is taking so long to get this resolved is there is more than just one system that the IP addresses have to be restored to. This is a very complex procedure to correct,” the email said.
The UK2 customer who brought the issue to Computer Weekly's attention was fuming because it had taken so long to fix.
The loss of all mail from users with BT Internet or Yahoo accounts for a day would be serious… a week is beyond belief
Francis Brown, UK2 customer
“I run a very small business, for which the loss of all mail from all users with BT Internet or Yahoo accounts for a day would be serious,” said Francis Brown, who previously worked at Imperial College London and now teaches computing courses in his retirement. “That the issue could have been permitted to drift on for a week is beyond belief.”
UK2 confirmed to Computer Weekly that there were issues with receiving emails from Yahoo accounts, but said the problem had been resolved yesterday, when all the affected IP addresses were whitelisted, enabling messages to come through again.
However, BT has yet to confirm why the blocks were put in place and said it is still investigating the reasons behind it.
Yahoo’s email service – Yahoo! Mail – runs on BT servers and often uses an @btinternet.com domain for the email address.
IP addresses are usually blocked if the users behind them are doing something wrong, such as sending out a lot of spam or hosting illegal material.