Getting tons of undelivery errors

[Spacedust]

I've started getting something like this:

Hi. This is the qmail-send program at mail.xxx.pl.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<sombodyspocket@gmail.com>:
User and password not set, continuing without authentication.
173.194.67.27 does not like recipient.
Remote host said: 550-5.1.1 The email account that you tried to reach does not exist. Please try
550-5.1.1 double-checking the recipient's email address for typos or
550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 http://support.google.com/mail/bin/answer.py?answer=6596 x16si6600471wiv.50 - gsmtp Giving up on 173.194.67.27.

--- Below this line is a copy of the message.

Return-Path: <kloxo@xxx.pl>
Received: (qmail 7080 invoked from network); 25 Jun 2014 12:48:05 -0000
Received: by simscan 1.4.0 ppid: 6385, pid: 7063, t: 0.2366s
         scanners: attach: 1.4.0 clamav: 0.98.3/m:55/d:19125
Received: from unknown (HELO xxx.pl) (kloxo@xxx.pl@178.35.168.237)
  by xxx.pl with ESMTPA; 25 Jun 2014 12:48:05 -0000
Message-ID: <ABB0F98B.838857BA@xxx.pl>
Date: Wed, 25 Jun 2014 16:48:09 +0400
From: "Mborjas" <kloxo@galeriaportali.pl>
MIME-Version: 1.0
To: <mborjas61@gmail.com>
Subject: Naughty bitches are ready to amaze you with their hot and sexy behavior!
Content-Type: text/plain;
   charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Nice to hear you,
 
A new girl waits to have a sexually intimate date this weekend.

Just go here to check up if you want to go on a date: 
http://InnoGam.es/e3bK 

These gals are ONLY searching for casual dates and sober-minded meetings.
You know them from school, from the gymnasium, they could be your neighbors.
 

Sincerly,   
XXXConnect Adult Dating Community 

----- 
Go here if you would like to not be contacted from us again:   
http://shorturl0.com/63868 

or write to: 

Stallion com FSC Limited  12 Kingslyn Ave., Kingston, W.I. 10 JM 

How to stop it ? Someone is trying to send e-mails from my mail !

[Spacedust]

It stopped when I changed my password