SMTP not being relayed to external Address


Using Free KEMP

Exchange 2016 with multiple receive connectors


Since installing Kemp (Hyper-V) I have noticed that any time one of our SMTP server that are allowed to send email to external address (i.e. monitoring services, Send to fax) that normally worked when connecting directly to the Exchange server, are being refused to relay anymore, getting in the log a "550 5.7.54 SMTP; Unable to relay recipient in non-accepted domain" message when going via the KEMP.

I am using the Kemp Template for Exchange 2016 SMTP.


Any idea what I should look for to troubleshoot/correct this problem?

Thanks in advance for any help/tips

Serge Ayotte

1 comment

Tony Vaughan

Hello Serge,

can you take a look at this article

what I am looking to confirm is the settings on the receive connectors on Exchange

if you are using the template then you would have the following settings enabled

transparency disabled
subnet originating requests enabled

with these settings the exchange server will see traffic with the source address of the LoadMasters interface
is this address on the receive connectors allowed list?