We are running Exchange 2013 CU2 on premises.  One user receive a message everyday at around 1:00pm and content are as follow:

-----Original Appointment-----
From: Microsoft Outlook On Behalf Of AAA@company.comSent: Thursday, June 12, 2014 1:07 AM
To: BBB@company.com
Subject: Weekly Conference Call

When: Occurs every Friday effective 3/14/2014 from 9:00 AM to 9:30 AM (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi.
Where: See Dial-In Numbers

When: Friday, June 13, 2014 9:00 AM-9:30 AM. (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi
Where: See Dial-In Numbers

Sent by Microsoft Exchange Server 2013

Doesn't anyone know what is happening?

Actually, I am experiencing the exact symptom as Office 365

http://community.office365.com/en-us/f/158/t/230472.aspx

Hi,

Please use EAC to check whether Journaling is configured in Exchange 2013 and this user is the journal recipient:

1. Navigate to Servers > Databases.

2. In the list view, double-click the mailbox database.

3. Click Maintenance, remove the journal recipient by clicking Remove X.

Hope it helps.

Regards,

Check the message header to find if it is Internal Message or coming from outside as a SPAM?

I am having the same problem, it is NOT related to Journaling!

Having the same issue as well.

We migrated from Exchange 2010 to Exchange 2013.  

Symptoms: Any user setups a meeting and unchecks "request responses".  The user will receive the meeting acceptance responses at 9pm at night from "Outlook on behalf of xxxxxx".

Is there a solution to this problem yet?