Over the past two years, the amount of spam, both as a total percentage
of email as well as the total number of spam messages per day, has doubled.
Based on our analysis we are making the following changes to protect you
from spammers, proactively address recent spam trends, and reduce the
overall volume of spam that you and your end-users must manage.
SUBLENIENT SPAM BLOCKING (SSB) ENABLED
SSB automatically removes the most blatant spam before it reaches your
servers, without requiring administrator or end-user intervention. The
messages identified by SSB (more than half of all spam messages) are not
quarantined—they are deleted.
To prevent your quarantine from being overwhelmed by blatant spam, SSB
will automatically be turned on for all organizations.
In rare cases, messages from mailing lists may be identified as spam by
SSB. To avoid this, add the sender or domain to the organization or end-user
Approved Senders list, as this list has precedence over SSB.
DIRECTORY HARVEST ATTACK PROTECTION
ENABLED
A directory harvest attack (DHA), is a technique used by spammers to obtain
lists of valid email addresses. During a DHA, spammers attempt to deliver
messages to multiple addresses, such as johndoe@yourcompany.com, jdoe@yourcompany.com,
and john@yourcompany.com. Addresses that are not rejected by the receiving
mail server are considered valid. These valid email addresses are compiled
into lists and immediately used to send spam. A successful DHA can net a
spammer thousands of email addresses in just a few minutes. Users whose
addresses are harvested quickly begin receiving an ever-growing amount of
junk email as spammers resell and exchange lists of known valid addresses.
DHA protection automatically detects and places a temporary block against
the offending IP. In order to protect you from spammers attempting to
harvest valid email addresses, DHA protection will always be active.
If you accept email from trusted servers or if your inbound email is
accepted by your email server and then routed out to Postini for filtering,
you will need to create a manual pass through for the email server IP. See
the attached FAQ document or the Knowledge Base in the Postini Support
Portal for instructions.
SPAM ATTACK PROTECTION ENABLED
Spam attacks occur when a single IP is identified as sending numerous spam
messages in a short period of time. Spam attack protection automatically
detects and places a temporary block against the offending IP. This feature
will always be enabled.
VIRUS ATTACK PROTECTION ENABLED
A virus attack is determined by both the ratio and volume of virus-infected
messages to valid email from an IP during a specific interval. If the ratio
increases in a statistically significant manner, the offending IP will be
temporarily blocked.
These changes are part of our ongoing efforts to improve email management
and will be effective April 29, 2004.
Should you have any questions, please contact Postini Technical Support
through your Support portal account. If you do not have a portal account,
request one by clicking the “Help” link near the bottom of the
Support Portal log in page. For
information on using the Support Portal to check system status, log cases,
query the knowledge base for solutions, and obtain support from Postini, see
the Postini Support Options document located on the
Activation webpage.
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