about spams

[Avi Greenbury]

Amaury Viera Hernández wrote:
> Hello, 
> I have a problem sending mails to gmail,
> every time that i send a mail i receive this answer:
> 
> this is the mail system at host mailserver.espnl.co.cu.
> 
> I'm sorry to have to inform you that your message could not
> be delivered to one or more recipients. It's attached below.

That message says

"Our system has detected an unusual rate of unsolicited mail
originating from your IP address."

so it sounds like someone is using your mailserver to send out spam.
Without knowing what you're running (though I guess Zimbra) it's hard
to tell you what to do next. 

It would be worth checking whether your mailserver is on a blacklist:

http://ip-blacklist.e-dns.org/

sometimes these give useful information as to what's being sent and
how; if you don't administer the server you should probably just pass
this on to the person who does.

-- 
Avi