SMTP Auth Issue

[JordanCook]

Postfix seems to allow anyone to send emails to domains that are configured in ISPConfig 3.

220 server1.mydomain.co.uk ESMTP Postfix (Debian/GNU)
MAIL FROM: someone@anywhere.com
250 2.1.0 Ok
RCPT TO: user@somewherelse.com
554 5.7.1 <jordan@somewherelse.com>: Relay access denied
RCPT TO: user@mydomain.co.uk
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Test
.
250 2.0.0 Ok: queued as 62C57876E

As you can see, it allows the user to send emails from any domain, to my domain without them having to login.

Can anybody help me?

Thanks,
Jordan Cook

[till]

Postfix seems to allow anyone to send emails to domains that are configured in ISPConfig 3.

Thats correct and the case on any mailserver. Otherwise, nobody would be able to send you any emails. So there is no problem with your system, it just does what a mailserver should do and that is to accept emails for the amilboxes that are configured on your server.