DNR Syntax

[bp1169]

I am curious if anyone has any reference for 'inbound notification failures', I receive quite a few nightly and would like to be able to translate them to see if there are any problems with my exchange server (open relaying, etc.) I have secured my exchange server to prevent relaying and my tests have shown it to be a closed system, however I receive strange DNR's, for example... 555 sorry, your envelope recipient is in my badrcptto list (#5.7.1) or 554 Client host rejected: cannot find your hostname, [xxx.xxx.xxx.xxx] These are inbound failures and really have me perplexed. I attempted to look for some syntax references to decode these but was unable. Any assistance is much appreciated. Thanks

 

[Zelandakh]

These are from spammers trying to see if any of your ports are open so they can relay through you.

They will probe entire subnets this way to find a way of running spam around the world.

Unfortunately, you just have to continue receiving them and deleting them as far as I know...