Question : Enabling SMTP Vrfy in Exchange 2000 & 2003

Hello,

I am looking for a way to enable the SMTP Vrfy command in Exchange 2000 and 2003 fto validate Email addresses for a front end SMTP relay.
]The firewall only allows SMTP port 25 traffic to the Exchange server from the relay IP adress, so there is no security risk.]

In Exchange 5.5, SMTP Vrfy can be easily enabled with a Windows registry entry:
Navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\MSExchangeIMC\Parameters
and add the following value:
Value name: EnableVRFY
Data type: REG_DWORD
Data: 0x1 (to enable)

As a first step I found the way to configure Exchange 2003 to check recipients in SMTP protocol
http://blogs.msdn.com/dlemson/archi...0/17/52019.aspx
This is not available in Windows 2000.

To prevent Email address harvesting, Exchange 2000 and 2003 disable SMTP Vrfy, and return instead:
> vrfy [email protected]
252 2.1.5 Cannot VRFY user, but will take message for <[email protected]>

This is confirmed by the microsoft support page: XIMS: VRFY Command Does Not Work in Exchange 2000 or in Exchange 2003
http://support.microsoft.com/defaul...kb;en-us;289521
This pages states that one need to write a 'protocol event sink' to do it.

The architecture is detailed at the page: Chapter 6: SMTP Transport Architecture
http://www.microsoft.com/technet/pr...9aa8c4ddf8.mspx in the paragraph SMTP Configuration Settings in the Metabase

SMTP events are described in MS Windows 2000 SMTP Service Events
http://www.microsoft.com/technet/pr...n/smtpserv.mspx

Another article: How to turn off ESMTP verbs in Exchange 2000 Server
and in Exchange Server 2003 http://support.microsoft.com/kb/257569 describes how to enable/disbaled some SMTP commands.
This is confirmed by the article listing Metabase S options (IIS metabase properties http://msdn.microsoft.com/library/d...4fcedd895e3.asp

The article Using the Metabase Reference Pages
http://www.microsoft.com/technet/pr...n/smtpserv.mspx listed a range of values defining the protocol behaviour, like:

Internal ID

Each property has a unique numerical identifier which IIS recognizes
internally. This is useful when writing C/C++ applications that use ABO.

Identifiers used by IIS are assigned from a pool of reserved numbers. If you create new identifiers in the metabase, use identifier numbers greater than 65535 (0x0000ffff) to avoid conflicts with current or future system data.
Identifiers are defined in the IIScnfg.h header file. The following ranges are reserved by IIS:

Range Reserved for
1 (0x00000001) to 32767 (0x00007fff) IIS identifiers.
28672 (0x00007000) to 32767 (0x00007fff) The subset of ASP identifiers.
32768 (0x00008000) to 36863 (0x00008fff) FrontPage Server Extensions identifiers.
36864 (0x00009000) to 40959 (0x00009fff) SMTP identifiers, owned by Exchange.
40960 (0x0000a000) to 45055 (0x0000afff) POP3 identifiers, owned by Exchange.
45056 (0x0000b000) to 49151 (0x0000bfff) NNTP identifiers, owned by Exchange.
49152 (0x0000c000) to 53247 (0x0000cfff) IMAP identifiers, owned by Exchange.
53248 (0x0000d000) to 57343 (0x0000dfff) MSCS identifiers.
57344 (0x0000e000) to 61439 (0x0000efff) Application Center identifiers.

It looks like the Windows SMTP server protocol behaviour can be defined by values (SmtpInboundCommandSupportOptions ?) either in the metabase IIS, or in the Active Directory configuration.

Not being a programmer, I cannot write a protocol event sink.

The issue is: how to enable the SMTP Vrfy command in Exchange 2000 and 2003 ?

Answer : Enabling SMTP Vrfy in Exchange 2000 & 2003

vrfy command is enabled in 2000 and 2003...but with a twist...it just does not tell u
whether user exists or not(and that is what u are looking for)...
but in 2003 if u enable filtering it will work the way u want it to work(like it did in 5.5)...read this article it will explain
http://support.microsoft.com/?kbid=842851