After a long absence returning to DLang...

I tried to register on RejectedSoftware Forums, but got an error:

(Expected status 250 in response to RCPT TO, got 554: 5.7.1 my.addie@gmail.com: Relay access denied).

I tried to re-register, but then the error changed to "User already exist". So it seems the user was created but, since I didn't get a activation mail, I requested a new activation mail. But then I again get the same (Expected status ... Relay access denied) error.

I tried on 2 different PCs (Win 10) with identical results.

Any ideas/hints/advice?

Ettienne