XFOR: IMC Support for VRFY Command
Article ID: 155684
Article Last Modified on 10/28/2006
APPLIES TO
- Microsoft Exchange Server 4.0 Service Pack 2
This article was previously published under Q155684
SYMPTOMS
The RFC 821 that defines the Simple Mail Transport Protocol (SMTP) states
that "The VRFY and EXPN commands are not included in the minimum
implementation." The VRFY command is used to verify that an address is
valid on a given SMTP host. This command is not implemented in the
Microsoft Exchange Internet Mail Connector (IMC), version 4.0. The use of
the VRFY command is considered a security hole by some organizations.
STATUS
Microsoft is aware that the VRFY command is used by some DNS registration
authorities for domain validation. For example, in France, the National
Network Information Center relies on an automatic procedure for verifying
that the Postmaster and Hostmaster E-mail addresses of a new DNS domain are
valid.
Microsoft has confirmed this to be a problem in Microsoft Exchange Server
version 4.0. This problem was corrected in the latest Microsoft Exchange
Service Pack. For information on obtaining the Service Pack, query on the
following word in the Microsoft Knowledge Base (without the spaces):
Additional query words: VRFY IMC XSRVInCon
Keywords: kbusage KB155684