Further information on implementing opportunistic TLS encryption for email servers can be found in the Australian Signals Directorate’s (ASD) Implementing certificates, TLS, HTTPS and opportunistic TLS publication.
Further information on implementing SPF, DKIM and DMARC can be found in ASD’s How to combat fake emails publication.
Further information on engaging the services of email service providers for marketing or filtering purposes can be found in ASD’s Marketing and filtering email service providers publication.
Further information on email content filtering can be found in the ‘Content filtering’ section of the Guidelines for gateways.
Further information on email content filtering can be found in ASD’s Malicious email mitigation strategies publication.
Further information on email security can be found in the following National Institute of Standards and Technology (NIST) publications:
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