Hello together,

On an Edge server 2013 we use some RBL blocklists. If a sending mail server is listed on a RBL it get an NDR 550 5.7.1 Recipient not authorized, your IP has been found on a block list".

We found this default text as not such useful in some cases and would like to customize it, e.g. to contain the RBL which show the IP as blocked. 

Is there a way to customize the NDR?

Thanks a lot
Max Kaiser

• Edited by Max Kaiser 19 hours 51 minutes ago

https://technet.microsoft.com/en-us/library/aa996803%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Hi Max,

If a match is found on the RBL provider list, SMTP issues a 550 5.x.x error in response to the RCPT TO command, and a customized error response is issued to the sender. 

However, we can customize response error by configure Connection Filtering. For your reference:
https://technet.microsoft.com/en-us/library/aa996146(v=exchg.65).aspx
https://technet.microsoft.com/en-us/library/bb124369(v=exchg.80).aspx