At times, you might want to identify a
specific email address or an entire domain on the Internet that is
sending you messages that you either want to completely allow or
specifically deny the receipt of messages from that source location.
The content filtering function of Edge Transport Services enables you
to create a white list that always allows content to be received from a
user or domain, or specifically allows for the denial of messages from
a user or domain.
Do note that each user
can also allow and deny message communications, so the choice to allow
or deny content at the server level should take into consideration that
the communications is organizationwide and that making a setting at the
Edge Transport server level will have a positive impact on the
appropriate receipt of content to all users in the organization.
An
example of a deny filter on a user address or entire domain would
include a situation where a user or domain is sending inappropriate
content to several users in the organization. Rather than having each
user make a configuration to block content from a user or domain, it
can be set at the server level.
Conversely,
if users in an organization want to receive all messages from a user or
domain, those names can be added to a white list that will always allow
messages to be received by users or the entire domain in the
organization.
Configuring the Content Filter Agent to Allow (White List) Specific Recipients, Senders, and Sending Domains
The
Exchange Management Console allows you to exclude specific keywords,
phrases, and recipients within your organization from content filtering
checks; however, you can only exclude specific senders and sending
domains from content filtering through the use of the Exchange
Management Shell’s Set-ContentFilterConfigBypassedSenders and BypassedSenderDomains parameters, respectively. command, using the
The BypassedSenders
parameter allows you to specify up to 100 external email addresses to
exclude from content filtering, with each entry separated by a comma.
Set-ContentFilterConfig –BypassedSenders [email protected], [email protected]
Note
The entry must be the full SMTP address; wildcard (*) use is not supported. For example, you cannot exclude john*@companyabc.com, or john@companyabc.*.
When excluding a specific email address (for example, [email protected]), consider whether it is safe to exclude the domain using the BypassSenderDomainscompanyabc.com). Not only does this save you time and message retrieval
because of false positives, it also consumes fewer entries in your
list, leveraging both lists and the allowed maximum of 100 more
efficiently. parameter instead (for example,
The BypassedSenderDomains parameter works similarly to the BypassedSenders
parameter, allowing you to specify up to 100 external domains to
exclude from content filtering, with each entry separated by a comma.
Set-ContentFilterConfig –BypassedSenderDomains *.companyabc.com, company123.org
Note
Wildcard use is supported to designate the exclusion of subdomains under the excluded domain, for example, *.companyabc.com.
Configuring the Content Filter’s SMTP Rejection Response
The
SMTP Rejection Response is inserted into a SMTP nondelivery report
(NDR) that is sent in reply to a rejected message. The default message
is Message Rejected Due to Content Restriction. This message can be
changed using the Set-ContentFilterConfig command with the -RejectionResponse parameter. The SMTP Rejection Response cannot exceed 240 characters and must be enclosed in quotation marks.
Note
Configuring
this feature is required if you have enabled message rejection for a
specific SCL threshold through the Exchange Management Console or the SCLRejectEnabled parameter of the Set-ContentFilterConfig command.
The SMTP Rejection Response cannot exceed 240 characters and must be enclosed in quotation marks.
Set-ContentFilterConfig -RejectionResponse "Message rejected, an error has occurred. Contact your HelpDesk"
