Exchange 2003 receiving large files issues

Yes.  They are in the same mailbox store.

Have you happened to receive one of the NDRs the senders are receiving?

Check their AD users and Computers account. You can set both the send and receive file limits.

change them from store default to an exceptable nuber e.g 10000 Kb or uncheck all boxes for unlimited send and recieve file sizes.

See below. I removed IP's as well as company information.  Thanks for looking into this....



This is the mail delivery agent at messagelabs.com.
I was not able to deliver your message to the following addresses.

failed after I sent the message.
Remote host said: 552 4.3.1 Message size exceeds fixed maximum message size


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

Return-Path: X-VirusChecked: Checked
X-Env-Sender:X-Msg-Ref: server-2.tower-152.messagelabs.com!1233090894!12606707!1
X-StarScan-Version: 6.0.0; banners=-,-,-
X-Originating-IP: Received: (qmail 22233 invoked from network); 27 Jan 2009 21:14:54 -0000
Received: from sigmail.comapny.com ()
(65.246.89.27)
  by server-2.tower-152.messagelabs.com with SMTP; 27 Jan 2009 21:14:54 -0000
Received: from mail3..NET (161.125.134.32)
      by(Sigaba Gateway v5.0)
      with ESMTP id 4927596; Tue, 27 Jan 2009 16:14:48 -0500
Received: from vo-dca-ex09.(unverified) by
    mail3.company.NET (Content Technologies SMTPRS 4.3.20) with
    ESMTP id <T8c2547c563a17d8620c14@mail3.>; Tue,
27
    Jan 2009 16:14:42 -0500
X-MimeOLE: Produced By Microsoft Exchange V6.5
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: multipart/mixed;
    boundary="----_=_NextPart_001_01C980C4.2CD18692"
Subject: Another test file:  You should DELETE from inbox and empty Deleted
    Items folder or these will freeze your Inbox due to over size limit
Date: Tue, 27 Jan 2009 16:11:41 -0500
Message-ID:
<5CB239653C33604E97D5C8D1FCF66BE70425472C@vo-dca-ex09..
NET>
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
Thread-Topic: Another test file: You should DELETE from inbox and empty
    Deleted Items folder or these will freeze your Inbox due to over size
    limit

On the user accounts check the following;

Exchange general - Delivery Restrictions

Exchange General - Storage Limits

Judging from the post above it looks like their mail boxes have reached the maximum limit set in either the store storage limits or their user personal storage limit.

If you "Up" the personal Storage Limit in AD Users and Computers this will over write the Exchange store limits. (Thisd will take upto 30 minutes to take effect)