mail from:xyz@COPSTOP 250 ok rcpt to:abc@COPSTOP.com 250 ok
As I have observed the server accepts message from xyz@COPSTOP to abc@COPSTOP.
If this is dangerous....assuming that i'am using sendmail, could u pls suggest a technique to stop this.
Yes I think this is bad. If the same server is acting as a mail relay for internal users and as an MX for that domain, then the solution may not be that simple. you could check this page out.
http://www.sendmail.org/%7Eca/email/check.html#check_rcpt
If this is only acting as an MX you can simply put this line in /etc/mail/access which i think might fix the problem (Not sure will have to try this out) and then makemap
From:copstop.com REJECT #will not accept from containing copstop.com In general check this page
http://www.sendmail.org/m4/anti_spam.html