OmniMessaging Functional Description 8.3

OmniMessaging Functional Description
07/22/04 Opsol Integrators Inc. Confidential and Proprietary Page 34 of 68
• Domain of sending MTA
• SMTP From Address
Each of the above can be blacklisted at the following levels:-
• System Level
• Domain Level (the local recipient’s domain)
Finally the system also allows SMTP From Address blacklisting at mailbox level.
Domain Level and Mailbox Level spam checking can be activated or inactivated
via system parameters (DOMAIN_LEVEL_SPAM_CHECKING,
MAILBOX_LEVEL_SPAM_CHECKING)
11.1.7 Pretension to Receive Spam
OmniMessaging by default rejects mail from blacklisted IP addresses, domains
or From Addresses. By enabling the Pretension flag the message is accepted
but later discarded. This feature does not allow the sender to know that the mail
is being rejected.
11.1.8 Relay Mail Blocking
When a message is received from an SMTP session with a recipient address
that is not local, then the message has to be passed out to a remote MTA. This
is relaying.
Within OmniMessaging relaying is allowed in the following cases:-
• the SMTP session has been authenticated via the SMTP auth
extension
• the SMTP session is from a local client (see subnet checking
below)
• POP Before SMTP is active and the SMTP client has already
logged in via POP or IMAP
• Whitelist Checking is enabled AND the domain for the recipient
address is present on the System Relay Whitelist table
N.B. If Whitelist Checking is not enabled, and the SMTP session does not
satisfy one of the first three criteria above, relaying is not allowed for the
session.
This Whitelist Checking is configurable on the MTA Send servers (NSIM-X-
CHECK-SYSRDTB server parameter).
Subnet checking is carried out against the IP address of the remote SMTP
client. If the check acknowledges that the client IP address is local, then
relaying is allowed.