My mail server start having mail with message saying (i change the ip for security reason).
Your mail 220.127.116.11:59431->18.104.22.168:25 is dropped for internal error.
I had about 2 of these per day, and they are real emails from people that we know. The sender of these emails are all from different domain. I could not find any similarities from any of these dropped emails.
I'm using Centos 4 with postfix + amavis-new + clamav + spamassissan. Everything is working just fine before last week.
I turn on debugging for the amavis-new log and couldn't find any kind of error message, beside of them say MIME type error (but this is only for one of the dropped mail).
I have no idea where to look. I don't even know if this error message is cause by my mail server or from outside.
somebody please help