My droplet is compromised and sending out spam.
I have received message from Admin:
We've detected the following spam being sent from your Droplet:
Received: from [18.104.22.168] by <removed> via sendmail with smtp;
for 1 recipient; Fri, 01 May 2015 20:57:42 -0000
Received: from vacinu (unknown [22.214.171.124])
by mail.hnhousing.com (Postfix) with ESMTPA id BCFCD139F00;
Fri, 1 May 2015 16:51:07 -0400 (EDT)
From: Info firstname.lastname@example.org
Subject: Fffd hi!
Date: Fri, 1 May 2015 12:37:10 -0700
X-Mailer: Microsoft Windows Live Mail 14.0.8089.726
X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8089.726
As a result, we've temporarily blocked mail traffic.
I'm a newbie. I don't know why. After that, I have been set up ssh key, UFW firewall. Are there any security problem ? How can I solve SMTP problem ? Please help me!