Postfix - Recipient address rejected

[Matt_Parfitt]

We are seeing a lot of email being rejected by postfix, some of which is legitimate email that should be delivered.

What I'm seeing from the maillog is logs such as the following;

NOQUEUE: reject: RCPT from unknown[Our IP Address]: 554 5.7.1 <Internal Email address>: Recipient address rejected: Access denied; from=<External Email Address> to=<Internal Email address> proto=ESMTP helo=<mail-pg0-f51.google.com>

We are seeing this repeatedly for different external domains. However the majority of mail is coming through ok.

I've been reading about editing main.cf postfix to change the line smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination to permit_unauth_destination.

Please can someone explain what this will do and if it will solve my problem?

Thanks,

[PhoneBoy]

If I understand correctly, the option disables the requirement to perform SMTP authentication when sending email to destinations.

Without other error logs, it's hard to say that will solve your problem or not.

[Thomas_Werner]

Hi Matt,

please don´t edit main.cf directly as it will be overwritten at each policy install.

Please use this: How to change Postfix configuration for Threat Emulation MTA 

Can you post more infos on your mailflow ?

NOQUEUE: reject: RCPT from unknown[Our IP Address]: 554 5.7.1 <Internal Email address>: Recipient address rejected: Access denied; from=<External Email Address> to=<Internal Email address> proto=ESMTP helo=<mail-pg0-f51.google.com>

Regarding the recipient´s email domain that is rejected here is the same domain accepted for other emails ?

What domains have you configured in the MTA settings to relay ?

Regards Thomas