Hi ,

We are using exchange 2013 server , We are getting mails from our mail service providers " arrowmail.co.uk" . Inside mails to "TO and FROM address are totally invalid.

Those users are not exist on my exchange server.

We have configured the address in our send connector " xx@arrowmail.co.uk " and route the mail using "smarthost.arrowmail.co.uk"

I tried to check my server on mxtoolbox and found its not and open relay , even though someone is logging

Is there any other possibilities , if my server is not an open relay ..what could be the security loop halls on my exchange i can check , and to stop those mails...or intruders are logging in to the server with faq id and trying to send to faq id and those failure messages are coming on admin id.

Thanks,

It doesnt matter if the inside of the headers are valid or not, what matters is the RCPT TO: or the Reply To or Return-path

BCC: is also popular with Spammers.

Hi ,

Thanks for your quick reply..

So , is there any way to stop those backscatter spamers..

Hi ,

Thanks for your quick reply..

So , is there any way to stop those backscatter spamers..

You would have to check with your anti-spam vendor. For EOP, they use:

https://technet.microsoft.com/en-us/library/Dn499795(v=EXCHG.150).aspx