How to turn off ESMTP verbs in Exchange 2000 Server and in Exchange Server 2003

Because of compatibility issues between Microsoft Exchange 2000 Server or Microsoft Exchange Server 2003 and other Simple Mail Transfer Protocol (SMTP) mail servers, you may have to turn off individual Extended Simple Mail Transfer Protocol (ESMTP) verbs that are advertised during the initial SMTP connection. This article describes the various settings that control the ESMTP advertisement.

By default, Exchange Server advertises the following ESMTP verbs. These verbs are controlled in the metabase and in Exchange Server event sinks. When you disable the event sinks, you may hinder Exchange Server performance. Therefore, this article focuses only on the ESMTP verbs that are controlled by the metabase.

The following verbs are controlled by the metabase:
Each of these verbs is represented by a hexadecimal value. These hexadecimal values are added to form a single number that represents the various on or off switches for these verbs. This number (in decimal format) is stored in the SmtpInboundCommandSupportOptions value, which can be found in under Lm/Smtpsvc/1LM in the metabase and in the msExchSmtpInboundCommandSupportOptions in the Active Directory under CN=1, CN=SMTP, CN=Protocols, CN=SERVER, CN=Servers, CN=First Administrative Group, CN=Administrative Groups, CN=Organization, CN=Microsoft Exchange, CN=Services, CN=Configuration, DC=domain, DC=com

NOTE: Where CN=1 is the first or Default SMTP Virtual Server, CN=SERVER is the servername of the Exchange Server, CN=Organization is the name of the organization, and DC=domain is the name of the Active Directory or Domain Name Server (DNS) domain.

Note that the metabase value listed above correlates to the metabase ID number 36998. This information may be useful when you are using the MetaEdit tool.

The following table lists the representation in hexadecimal.


Chunking cannot be disabled explicitly. That is, if we subtract the value of chunking (1048576) from the default (7697601) and configure 6649025 on msExchSmtpInboundCommandSupportOptions, the chunking verb is still displayed.

To disable chunking, add 7697601 - (chunking + binarymime) or 7697601 - (chunking + 8bitmime) and configure the resultant value.

Prior to Microsoft Exchange 2000 Server, this value could be modified in the metabase using tools such as CSCRIPT with Adsutil.vbs or MetaEdit. However, in Exchange 2000 Server and in Microsoft Exchange Server 2003, values in the metabase are subordinated to values in the Active Directory. A process called the "Microsoft Exchange Metabase Update" service (listed as MSExchangeMU in the Application event log) runs every 15 minutes and compares the values in the metabase with corresponding values in Active Directory. If the values are different, then the value in the metabase is overwritten with the value from the Active Directory. Thus, in order to make these changes effective, you must modify the msExchSmtpInboundCommandSupportOptions value in the Active Directory using either LDP or ADSIEdit.

To modify this value by using ADSIEdit, complete the following steps:

1. Open ADSIEdit and connect to a domain controller.
2. Open the Configuration Container.
3. Navigate to the following location:
   Configuration/Services/Microsoft Exchange/ <Your Organization>/ Administrative Groups/<Your Administrative Group>/Servers/ <Your Exchange Server>/Protocols/SMTP/ <Your Virtual Server Number>
4. Right-click the virtual server object, and then click Properties.
5. For Select a property to view: select msExchSmtpInboundCommandSupportOptions.
6. In the Edit Attribute: field, enter the value you want to set.
   
   NOTE: This value is based on the summation of values from the table above.
7. Click Set, Apply, and then OK.
8. Exit out of ADSIEdit.

There may be a delay before this change takes effect because Active Directory replication may be required before the specified Exchange Server sees the value you have modified. Internal tests discovered that to restart the Internet Information Server (IIS) Administration Service may not force the update to occur faster.

NOTE: ADSIEDIT.exe is graphical administrative tool which is part of the Windows 2000 Support Tools, which are available on the Windows 2000 installation CD-ROM in the \Support\Tools directory.

NOTE: If you disable ESMTP verbs on an Exchange Server, this may affect communication with other Exchange Servers. The effects may include breaking normal mail flow between servers.