"501 5.5.4 Invalid Address" error message from a sending UNIX server

If a user tries to send mail to a Microsoft Exchange Server computer by using UNIX Send Mail, the Exchange Server computer receives a "501 5.5.4 Invalid Address" error message. You can verify this by creating a telnet session to port 25 of the Exchange computer: Note You can only detect this error message by creating a telnet session to the receiving Exchange computer. This error message does not appear in a dialog box on the receiving Exchange computer and is not logged in the application event log of the receiving Exchange computer.

This problem may occur if the UNIX sending server is not in accordance with the Request for Comments (RFC) 821 and RFC 1869 documents. The receiving Exchange computer expects either a host name only or a fully qualified domain name (FQDN) following the EHLO/HELO command. A trailing dot after the FQDN is interpreted as incorrect syntax, and a 501 error message is generated.

Note A trailing space also generates this error message.

Exchange Server 5.5 SP4, Exchange 2000 Server, and Exchange Server 2003 do not permit trailing spaces and trailing dots. This is in accordance with the RFC 821 and RFC 1869 documents. However, some Simple Mail Transfer Protocol (SMTP) hosts, such as Send Mail servers, do permit trailing spaces and trailing dots.

Exchange Server 5.5 and Exchange 2000 Server

To work around this problem in Exchange Server 5.5 SP4 or in Exchange 2000 Server, follow these steps:

1. Install MetaEdit 2.0 or later on the receiving server.
2. Start MetaEdit, and then expand the LM root folder.
3. Click SmtpSvc, right-click SmtpSvc, click New, and then click DWORD. Leave the ID box set to Other, but change the numeric value from 0 to 36992.
4. Add the Attribute of Inherit. Leave the User Type set to Server, and leave the Data Type set to DWORD.
5. Change the Data box to a value of 1.

Exchange Server 2003

To work around this problem in Exchange Server 2003, follow these steps.

Note MetaEdit does not work with IIS 6.0. Therefore, you may have to download the IIS 6.0 Resource Kit tools to complete the following procedure. To download the IIS 6.0 Resource Kit tools, visit the following Microsoft Web site:

1. Start MetaBase Explorer.
2. In the left pane, expand the LM branch, right-click SmtpSvc, point to New, and then click DWORD record.
3. In the Record Name or Identifier box, type 36992, and then click OK.
4. In the right pane, double-click the 36992 SmtpDomainValidationFlags line.
5. In the Value box, type 1.
6. Click the General tab, set the user type to server, click to select the Inheritable check box, and then click OK.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.