Lotus Domino Administrator 8 Help - Supporting inbound SMTP extensions

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Supporting inbound SMTP extensions
IBM® Lotus® Domino™ supports a number of extended SMTP (ESMTP) functions. These include the ability to combine (or "pipeline") commands, set the server to check message size before accepting transfer, create a secure SSL connection with another server, and create delivery status notifications in MIME format. You enable or disable each of these options in the Configuration Settings document for the server or servers for which you want to use these extensions.

1. Make sure you already have a Configuration Settings document for the server(s) to be configured.

2. From the Domino Administrator, click the Configuration tab and expand the Messaging section.

3. Click Configurations.

4. Select the Configuration Settings document for the mail server or servers you want to administer, and click Edit Configuration.

5. Click the Router/SMTP - Advanced - Commands and Extensions tab.

6. Complete these fields in the Inbound SMTP Commands and Extensions section, and then click Save and Close:

Field Enter

SIZE extension Choose one:

Enabled - (default) Domino declares its maximum message size to connecting hosts and checks the sending host's estimates of message size before accepting transfer. If the sender indicates that a message to be transferred is larger than the maximum size, Domino returns an error indicating that it will not accept the message.
Disabled - Domino does not advertise its maximum message size or check inbound message size before transfer.
Note For information about setting the maximum message size, see the topic "Restricting mail routing based on message size" earlier in this chapter.

Pipelining extension Choose one:

Enabled (default) - Improves performance by allowing Domino to accept multiple SMTP commands in the same network packet.
Disabled - Domino does not accept multiple SMTP commands in a single packet.

DSN extension Choose one:

Enabled - Domino supports incoming requests to return delivery status notifications to the sender for failed, delayed, delivered, and relayed messages. Domino sends delay reports for low-priority messages held until the low-priority routing time to the sender of an SMTP message upon request.
Disabled - (default) Domino does not return delivery status notifications for SMTP messages.

8-bit MIME extension Choose one:

Enabled - Domino accepts 8-bit messages as is, allowing reception of unencoded multinational characters.
Disabled (default) - Domino requires inbound messages containing 8-bit characters to be sent using 7-bit ASCII encoding.

HELP command Choose one:

Enabled - (default) In response to the Help command, Domino displays a list of supported commands.
Disabled - Domino ignores the Help command.

VRFY command Choose one:

Enabled - Domino accepts inbound requests to verify user names.
Disabled - (default) Domino denies requests to verify user names.

EXPN command Choose one:

Enabled - Domino expands mailing lists or groups to show individual recipient names.
Disabled - (default) Domino does not expand lists and groups.

ETRN command Choose one:

Enabled - Domino accepts inbound "pull" requests from other SMTP hosts to transfer messages destined for the calling server. Enabling ETRN support allows for more efficient use of bandwidth resources by allowing a remote SMTP host to request pending messages at the same time it transfers messages to the Domino server.
Disabled - (default) Domino does not accept inbound "pull" requests from other SMTP hosts.

SSL negotiated over TCP/IP port Choose one:

Enabled - Domino supports the STARTTLS command, allowing it to create an encrypted SSL channel over the SMTP TCP/IP port.
Required - Domino accepts inbound SMTP connections over the TCP/IP port only from hosts that issue the STARTTLS command.
Disabled (default) - Domino does not allow secure SSL connections over the SMTP TCP/IP port.
Note After accepting the STARTTLS command from a remote server, Domino uses settings for the server's SSL port to govern authentication for the sessions. For Domino to authenticate remote hosts that use the SMTP AUTH command, Name & Password authentication must be enabled for the Domino SSL port.

7. Reload the SMTP task, or update the SMTP configuration to put changes into effect.

Note Enabling VRFY and EXPN allows people outside your organization to expand group names and to check for valid e-mail addresses in your organization. You may not want to enable these extensions for security reasons.

See also

Restricting SMTP inbound routing

Securing SMTP sessions using the STARTTLS extension

Restricting users from receiving Internet mail

Supporting outbound SMTP extensions

Changing the inbound SMTP port settings

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Glossary

Field	Enter
SIZE extension	Choose one: Enabled - (default) Domino declares its maximum message size to connecting hosts and checks the sending host's estimates of message size before accepting transfer. If the sender indicates that a message to be transferred is larger than the maximum size, Domino returns an error indicating that it will not accept the message. Disabled - Domino does not advertise its maximum message size or check inbound message size before transfer. Note For information about setting the maximum message size, see the topic "Restricting mail routing based on message size" earlier in this chapter.
Pipelining extension	Choose one: Enabled (default) - Improves performance by allowing Domino to accept multiple SMTP commands in the same network packet. Disabled - Domino does not accept multiple SMTP commands in a single packet.
DSN extension	Choose one: Enabled - Domino supports incoming requests to return delivery status notifications to the sender for failed, delayed, delivered, and relayed messages. Domino sends delay reports for low-priority messages held until the low-priority routing time to the sender of an SMTP message upon request. Disabled - (default) Domino does not return delivery status notifications for SMTP messages.
8-bit MIME extension	Choose one: Enabled - Domino accepts 8-bit messages as is, allowing reception of unencoded multinational characters. Disabled (default) - Domino requires inbound messages containing 8-bit characters to be sent using 7-bit ASCII encoding.
HELP command	Choose one: Enabled - (default) In response to the Help command, Domino displays a list of supported commands. Disabled - Domino ignores the Help command.
VRFY command	Choose one: Enabled - Domino accepts inbound requests to verify user names. Disabled - (default) Domino denies requests to verify user names.
EXPN command	Choose one: Enabled - Domino expands mailing lists or groups to show individual recipient names. Disabled - (default) Domino does not expand lists and groups.
ETRN command	Choose one: Enabled - Domino accepts inbound "pull" requests from other SMTP hosts to transfer messages destined for the calling server. Enabling ETRN support allows for more efficient use of bandwidth resources by allowing a remote SMTP host to request pending messages at the same time it transfers messages to the Domino server. Disabled - (default) Domino does not accept inbound "pull" requests from other SMTP hosts.
SSL negotiated over TCP/IP port	Choose one: Enabled - Domino supports the STARTTLS command, allowing it to create an encrypted SSL channel over the SMTP TCP/IP port. Required - Domino accepts inbound SMTP connections over the TCP/IP port only from hosts that issue the STARTTLS command. Disabled (default) - Domino does not allow secure SSL connections over the SMTP TCP/IP port. Note After accepting the STARTTLS command from a remote server, Domino uses settings for the server's SSL port to govern authentication for the sessions. For Domino to authenticate remote hosts that use the SMTP AUTH command, Name & Password authentication must be enabled for the Domino SSL port.