XFOR: IMS Support for user@[IP Address] Format per RFC821

• Microsoft Exchange Server, version 5.5

SUMMARY

In Microsoft Exchange Server versions 4.0 and 5.0, it is not possible to send messages to a user using the format "user@[IP Address]". However, per RFC 821 and 821bis this is a valid addressing format.

Microsoft recognizes the need for compliance to this RFC specification. Microsoft Exchange Server version 5.5 will allow for this addressing method and will, therefore, allow messages to be sent using this format. The feature involves a modification to the Exchange Server Internet Mail Service to now understand IPv4 literals. The Internet Mail Service is now capable of accepting mail inbound, delivering outbound, and rerouting mail addressed in the format "user@[IP Address]," also known as IPv4 literal.

NOTE: The admin does not allow you to create a proxy of the form 'user@[IP Address]' (it will strip the brackets).

For more information, please see the following Microsoft Knowledge Base article:

Q193316 XFOR: How to create addresses of form 'user@[IP Address]

MORE INFORMATION

Per RFC 821 page 31:

Hosts are generally known by names, which are translated to addresses in each host. Note that the name elements of domains are the official names -- no use of nicknames or aliases is allowed. Sometimes, a host is not known to the translation function and communication is blocked. To bypass this barrier, two numeric forms are also allowed for host "names". One form is a decimal integer prefixed by a pound sign, "#", which indicates the number is the address of the host. Another form is four small decimal integers separated by dots and enclosed by brackets, for example, "[123.255.37.2]", which indicates a 32-bit ARPA Internet Address in four 8-bit fields.

Additional query words: IPv4-literal, RFC821, 821bis

Keywords          : 
Version           : WinNT:5.5
Platform          : winnt 
Issue type        : kbinfo 

Last Reviewed: April 19, 1999