04-12-2019, 01:45 PM
501 is not an Indy error. This error is coming from the server and most likely a server based problem. From the very link you posted which appears Indy is not involved there at all yet:
" In a short test it seems that the SMTP server of your provider doesn't like the "_" character in your hostname. I'll see how I can change that and what the official RFC says about that. Thanks for the report and the debug log."
It looks like an improperly configured server unless there is an encoding issue for which _ does not require such AFAIK.
" In a short test it seems that the SMTP server of your provider doesn't like the "_" character in your hostname. I'll see how I can change that and what the official RFC says about that. Thanks for the report and the debug log."
It looks like an improperly configured server unless there is an encoding issue for which _ does not require such AFAIK.