Defining the maximum error limit before a connection terminates

You can specify the number of protocol errors that can be returned for a session before the session connection is terminated. When the number of errors returned for a session exceeds the specified value, the session is terminated. For example, blacklist rejections and RCPT To rejections are protocol errors.

About this task

When a connection is terminated because the error limit is exceeded, the following message displays:

421 SMTP service not available, closing transmission channel.

You can use the Configuration Settings document or the NOTES.INI file setting, SMTPErrorLimit, to specify the SMTP error limit. If both settings are used, the NOTES.INI file setting takes precedence over the setting in the Configuration Settings document.


  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 > Restrictions and Controls > SMTP Inbound Controls tab.
  6. In the Inbound Connection Controls section, in the field Error limit before connection is terminated, specify the maximum number of protocol errors allowed before a session connection is terminated.
  7. Click Save and Close.