SMTP madness!

My PostCast SMTP server is buried in messages. This has never happened before today. The messages-per-hour is now at 4,000-something. Norton AntiVirus is on, as usual, and scanning all of them.

Is this normal? Should I send on the messages or stop them?

Also, many of them are in Chinese.

They're from seed.net. yahoo.com.tw, hotmail.com, ms##.hinet.net, ibm.com, life-ideas.com, geocities.com, netvigator.com, usa.net, sinamail.com, hkstar.com, ibm.net, yahoo.com, yammail.com, to name a small few. They seem to be coming from everywhere...

UPDATE: They were all the same message. I ended the PostCast process.

one more spammer immobilized wd

Be sure that relay domains list is empty (at least trusted ones) .
If you have any demo account , do not forget that the demo accounts are the easiest and best way to spam the world for the useless men, for the men whom are overwhelmed and try to make their ego by those simple ways...,
I got trouble with the spammers too much before, so i have experienced too much too and i am helping everyone to save theirselfs from the spam.

Just tell your your control (if it is cpanel or ensim) i would help you about the exact solution for those kind of spams

Don't have any control panel.

How do you add/delete/modify domains ?

At least is exim.conf managing your mailserver ? is this file exist within your server?

No it doesn't. I'm using PostCast SMTP server. (forgive the link)