Applies to all Email Security Gateways.
The Check SPF for Bounce Recipients setting is configured in Advanced > Bounce/NDR settings > Spam Bounce (NDR) Configuration. This configuration option differs from the SPF Configuration settings on the Block/Accept > Sender Authentication page in that the SPF Configuration settings decide whether SPF lookups should be used to determine if an email is spam. The Check SPF for Bounce Recipients option decides whether an SPF lookup should be performed after a message has already been determined to be spam. This prevents your Email Security Gateway from sending email bounce messages to forged sender addresses.
Regardless of this setting, no bounce message will ever be issued for messages that were determined to be spam because of SPF match failures; thus, it is unnecessary to enable this option if general SPF checking has been enabled.
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