[quote user="lananhbin"]i log in web mail of zimbra and that user is sending randomly thousand of emails. thats emails make my system crash !
ex : my domain is abc.cd.ef so my user email is : email@example.com
[/QUOTE]I understand that.
[quote user="lananhbin"]but the email sending spam is firstname.lastname@example.org
. and z.abc.cd.ef is the FQDN of my mail server.
i cant find that user ![/QUOTE]You still haven't said how you know this 'user' is sending spam, where did you get that email address from? If you got this from the log files then you should see the IP address of the client that's submitting the email. If you have no user with that name on your ser then you've either got a compromised account or a spam bot on your network that's submitting mail through your server.
[quote user="lananhbin"]p.s: i searched but i cant find any solution[/QUOTE]There are plenty of solutions in the forums, I'd suggest you look at some of those threads that discuss 'compromised accounts' and try some of the suggestions you'll find. You will additionally need to look at your log files to find the source of this problem, merely repeating the suspected user name does not give enough information anyone to advise you - you're going to have to do some digging in the log files.