I have recently become aware of a problem with my PMs.

I can send PMs with no problems but someone tried to PM me but it appears his messages were blocked and I did not receive them. To contact me he sent me a site dollar to which he could add a message. This I received.

I assume I have changed something in my configuration which stops me receiving PMs. I have searched through the configuration screens but cannot find anything.

Please tell me what I am missing.

[Disk4mat]

I fixed it for you. The setting was:
"Allow users to send you private messages:" - you had it set to No.
ucp.php?i=165