My server log ( qmail ISOqLog ) say 1.000.000 mail sends in a day.
After i examine
1- #@[] send ~500.000 messages sended.
( no such user #@[] in my system )
2- name1@customerdomain.com ~500.000
( customerdomain not have name1 mail account )

How to find sender ?

I try multiple open relay checker. My server not listed in these list , and try open relay. It says this server secured and not open for relay.

I think it will be from phpscript ?

How to find spammer ?

 

I believe those would be emails 'received' by the mail server, not sent out from your mail server. The '#@[]' is currently a common spammer technique, but I have only seen them for incoming emails being sent in to the server, not outgoing.

 

what can i do ?

How can i solve this problem ?