email error from [email protected] (Site under attack ?)

[FlavioP]

Every single day I get an email like this one below into my email-spam folder…:
… and I don’t know what it is about.
I suspect someone is trying to get access to my site...
Can anyone help me in shaping what sort of problem might be ?
.....................................................................................................

[email protected]
Hi. This is the qmail-send program at web.giove.vhosting-it.com.
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.

<[email protected]>:
46.22.173.251 failed after I sent the message.
Remote host said: 421 Unexpected log failure, please try later I'm not going to try again; this message has been in the queue too long.

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

Return-Path: <[email protected]>
Received: (qmail 286873 invoked by uid 10218); 23 Aug 2014 22:43:09 +0200
To: [email protected]
Subject: Dettagli account per XXXXXX su Melogranello
Date: Sat, 23 Aug 2014 20:43:09 +0000
From: Melogranello <[email protected]>
Message-ID: <[email protected]>
X-Priority: 3
X-Mailer: PHPMailer 5.2.6 (https://github.com/PHPMailer/PHPMailer/)
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit

THEN A MESSAGE IN ITALIAN IS WRITTEN AS PER BELOW TRANSLATION....

Hi XXXXX,

Thanks for registering on Melogranello. Your account has been created and must be activated before you can use it.
To acivate it click on the following link:

http://melogranello.it/index.php/co...tivate&token=dbb0cd250fbc44150b7f46bd137d0231

After that, you could access the reserved area of http://melogranello.it/ using the following username and password:

Nome utente: XXXXXX
Password: YYYYY

 

[IgorG]

I don't understand how it is related to Plesk for Windows, but I think it is just usual spam.