I ran into this error when attempting to send local e-mail from my postfix box which sits on the same network as my Microsoft Exchange 2003 server.
554 5.1.0 Sender Denied (in reply to end of DATA command)
The solution to this problem is to disable sender/recipient filtering in Microsoft Exchange.
Exchange System Manager.
2. Right Click on
Message Delivery and select
3. Browse to the
Recipient Filter tab and uncheck
Filter recipients who are not in the directory.
Within Exchange System Manager, expand the following:
Servers > "Your Server" > Protocols > SMTP
Right click on
Default SMTP Virtual Server and select
Advanced within the
General tab and then click on
Apply Sender Filter and
Apply Recipient Filter.
Restart the SMTP service from the command line:
net stop "Simple Mail Transfer Protocol (SMTP)"
net start "Simple Mail Transfer Protocol (SMTP)"
This solution was derived from this website.