I’ve been seeing reports for the last few weeks that a lot of folks are having problems getting mail into BT Internet. Many people are reporting the response
smtp;554 Message rejected for policy reasons (188.8.131.52) – Please report any problems to BT via the postmaster btinternet.com mailbox and include your sending ip address with an example header of your email
Unfortunately, the postmaster account appears to not be as responsive as it used to be. This may be a consequence of the move from Yahoo to Critical Path and then CP being bought by Openwave.
One thing people are suggesting is that valid and correct SPF records are crucial for delivery to BT Internet. I don’t know if this is really the fix, and many of the companies reporting the problem have valid SPF records. But it’s always a good idea to check your SPF with our authentication checking tool.