Mail flow

This section describes the configuration of mail flow within Exchange Online associated with systems built according to guidance in ASD's Blueprint for Secure Cloud.

Estimated reading time: 2 minutes

Instruction

The below pages outline the as built configuration for ASD’s Blueprint for Secure Cloud (the Blueprint) for the Microsoft Exchange admin portal at the following URL:

https://admin.exchange.microsoft.com/#/settings

The settings described on these pages provide a baseline implementation for a system configured using the Blueprint. Any implementation implied by these pages should not be considered as prescriptive as to how an organisation must scope, build, document, or assess a system.

Implementation of the guidance provided by the Blueprint will differ depending on an organisation’s operating context and organisational culture. Organisations should implement the Blueprint in alignment with their existing change management, business processes and frameworks.

Placeholders such as <ORGANISATION.GOV.AU>, <BLUEPRINT.GOV.AU> and <TENANT-NAME> should be replaced with the relevant details as required.

General

Item	Value
Turn off plus addressing for your organisation	Not checked
Turn on sending from aliases	Not checked

Security

Item	Value
Turn off SMTP AUTH protocol for your organisation	Checked
Turn on use of legacy TLS clients	Not checked

Reply-all Storm Protection

Item	Value
Enable reply-all storm protection	Checked
Minimum number of recipients	2500
Minimum number of reply-alls	10
Block duration	6

Message Recall

Item	Value
Enable cloud-based message recall	Checked
Allow users to recall messages read by the recipient	Checked
Enable recall alerts for recipients	Checked
	Only for recalled messages that were read by the recipient
Do not allow senders to recall messages older than this	1 Day