I was hapy Zimbra user for three years until few hours ago, now when i try to send email i get following error:
This is the mail system at host mx3.elite.hr.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<srdjankadric@gmail.com>: host 195.29.150.5[195.29.150.5] said: 550 5.7.1
<unknown[195.29.121.38]>: Client host rejected: Blocked because of
spam/virus. Please contact abuse@t-com.hr for more info. (in reply to RCPT
TO command)



Reporting-MTA: dns; mx3.elite.hr
X-Postfix-Queue-ID: BF54524335B0C
X-Postfix-Sender: rfc822; admin@elite.hr
Arrival-Date: Thu, 25 Jul 2013 23:24:02 +0200 (CEST)

Final-Recipient: rfc822; srdjankadric@gmail.com
Original-Recipient: rfc822;srdjankadric@gmail.com
Action: failed
Status: 5.7.1
Remote-MTA: dns; 195.29.150.5
Diagnostic-Code: smtp; 550 5.7.1 <unknown[195.29.121.38]>: Client host
rejected: Blocked because of spam/virus. Please contact abuse@t-com.hr for
more info.

Is my server on black list??