Client does not have permission to Send As this sender.



One of our customers is facing a problem in Exchange 2000 server. Here is the
problem description



Exchange 2000 Enterprise Version 6.0(Build 6249.4: Service Pack 3) is
running in Front-end and Back-end topology. Customer has three Exchange
front-end server, one of them is being used by POP3 users. They use both POP3
and SMTP of that server. Customer has removed Anonymous Access from Access
Controlà Authentication tab under Default SMTP Virtual Server so that anyone
who wants to use SMTP should authenticate first. On client side, users are
specifying that My outgoing SMTP server requires authentication.
Authenticated SMTP is working fine for most of the POP3 users but some are
getting the following error messages.



1) The message could not be sent because the server rejected the
sender's e-mail address. The sender's e-mail address was 'roy@xxxxxxxxxx'.
Subject '', Account: 'mailgate.1234ac.com', Server: 'mailgate.1234ac.com',
Protocol: SMTP, Server Response: '454 5.7.3 Client does not have permission
to Send As this sender.’ Port: 25, Secure(SSL): No, Server Error: 454, Error
Number: 0x800CCC78



2) Event Type: Warning

Event Source: MSExchangeTransport

Event Category: SMTP Protocol

Event ID: 1710

Date: 4/25/2006

Time: 4:57:52 PM

User: N/A

Computer: MAILGATE02

Description:

The SMTP client "86.96.96.1" authenticated as user "xxxx\a9254" attempted to
send as "ashraf@xxxxxxxxxx". Access was denied because the authenticated
client does not have permission to Send As this SMTP address.

Data:

0000: 05 00 07 80



3) Event Type: Warning

Event Source: MSExchangeTransport

Event Category: SMTP Protocol

Event ID: 1711

Date: 4/25/2006

Time: 5:00:36 PM

User: N/A

Computer: MAILGATE02

Description:

The SMTP client "82.76.194.190" authenticated as user "xxxx\ZSBucharest"
attempted to send as "zsbucharest@xxxxxxxx". Access was denied because the
sender's SMTP address does not exist.

Data:

0000: 05 00 07 80



All these users have valid AD accounts. They get these messages even sending
internally or sending to themselves. Server has Trend micro Antivirus
installed with latest pattern file.







There are almost 100 users who are using this service and approx. 15 of the
users are facing problem.
If administrator deletes and recreated the user Account then users can send
an email.

.