Mail problems with @php.net challenge-response

Hello, I'm getting problems with my @php.net mail. I can't receive a message from it. Could you, please, investigate this issue more make a short summary, because I believe the problem is not new? Perhaps we could elaborate on a solution. Short history - recently (a week ago) I've got an email from forums@wsus.info (unsure if "forums" was plural). The mail appeared among challenge-response mails blocked by server and I successfully confirmed its "legitimate" status. However, I haven't received it yet. I do not know how many emails are gone unnoticed in the past, because approval system doesn't work as expected, but I can hardly remember any new addresses in the messages sent to techtonik//at//php/net during past three months. -- --t.