MainSleaze

Social networking site LinkedIn is sending invitations to join both to email addresses that never existed and email addresses that might have existed many years ago but not in the past few years. LinkedIn does not appear to do any vetting of email addresses that its users provide to it, leading it to send invitation emails to many spamtraps on a regular basis. It then sends reminders about email that was unsolicited in the first place.

Sending IP: 216.52.242.160

Spam Sample:

Actual Headers:

Received: from maild-bc.linkedin.com (maild-bc.linkedin.com [216.52.242.160])
        by <xxx> (Postfix) with ESMTP id <xxx>
        for <xxx>; Tue, 18 Oct 2011 02:xx:xx -0500 (CDT)
DomainKey-Signature: <xxx>
DKIM-Signature: <xxx>
Sender: messages-noreply@bounce.linkedin.com
Date: Tue, 18 Oct 2011 07:xx:xx +0000 (UTC)
From: "<xxx> (LinkedIn  Invitations)" <invitations@linkedin.com>
To: <xxx>
Message-ID: <<xxx>.JavaMail.app@ela4-app0057.prod>
Subject: Reminder about your invitation from <xxx>
MIME-Version: 1.0
Content-Type: multipart/alternative;
        boundary="----=_Part_<xxx>"
X-LinkedIn-Template: inv_exp_17
X-LinkedIn-Class: INVITE-REMIND-GUEST
X-LinkedIn-fbl: <xxx>

Readable Email:

From: <xxx> (LinkedIn Invitations) <invitations@linkedin.com>
To: <spamtrap>
Subject: Reminder about your invitation from <xxx>

This is a reminder that on October 13, <xxx> sent you an invitation to become part of their professional network at LinkedIn.

Accept <xxx> Invitation

———-
On October 13, <xxx> wrote:

> To: <spamtrap>
> From: <xxx>
> Subject: Invitation to connect on LinkedIn
>
> <xxx>,
>
> I’d like to add you to my professional network on LinkedIn.
>
> – <xxx>

———-

You are receiving Reminder emails for pending invitations. Click to unsubscribe:
http://www.linkedin.com/e/<xxx>