DTM Smtp Interceptor
The DTM SMTP Interceptor is designed to intercept
and block unwanted SMTP connections. Its engine
operates with internal actions, while a Notes
database configuration file enables Domino
administrators to whitelist or blacklist specific
domains or IP addresses. For example, the tool can
be used to prevent certain users from connecting to
the mail server via SMTP and ban them.
Fail2ban integrated to Linux is used by the system
to block incriminated inbound IP addresses. The DTM
SMTP Interceptor records hostnames and IP addresses
in the appropriate format for use with Domino-SMTP
or Domino filters applied by Fail2ban, as logged in
HCL Domino logs. This ensures streamlined management
of unwanted connections and enhances security
measures for the mail server.
DTM Smtp Interceptor Configuration
The configuration is done via documents in a HCL
Notes Database, modifications are dynamic, there is
no need to restart the HCL Domino server.
Whitelisted Domains or IP addresses (IPv4, IPv6, or CIDR) allow administrators to
bypass controls for specified Internet Domains or IP
addresses, granting access to the SMTP inbound of
Domino even when blacklist options are applied.
Blacklisted Domains or IP addresses (IPv4, IPv6, or CIDR) enable administrators to
block access from specific Internet Domains or IP
addresses entirely.
Administrators can blacklist certain SMTP commands or restrict the set of allowable SMTP
commands. For standard SMTP commands, specific
commands can be refused even if they lack
parameters.
For EHLO/HELO, administrators can blacklist any SMTP Hello
command based on two configurable options: empty
EHLO/HELO (Domino will not respond) and prohibiting
specific EHLOs/HELOs.
For MAIL FROM, administrators can blacklist any SMTP "Mail From"
address and block SMTP connections.
For recipients, administrators can blacklist recipients using two
configurable options: setting a maximum number of
accepted recipients and prohibiting specific
recipient email addresses.
DTM Smtp Interceptor Logging
The logging of incoming SMTP emails is stored as
documents in an HCL Notes Database. The recording of
information is dynamic, but the email body is not
logged to ensure security and privacy.
