Exchange Online in practice.
WHAT IT PROVIDES
Mailboxes, calendars and contacts Shared mailboxes, requiring no licence Distribution groups Rules and retention policies Protection against spam and malicious content
WHAT TO CONFIGURE FOR YOUR DOMAIN
The records directing mail to the service The records authorising which servers may send for your domain A signing arrangement for outgoing mail A policy telling receivers what to do with failures
WHY THOSE LAST THREE MATTER
Without them, your mail is filtered or rejected by other providers.
WHAT TO SET THAT POLICY TO INITIALLY
Monitoring only, then progressively stricter once reports show legitimate sources are covered.
WHY
Setting it strictly first blocks legitimate mail you forgot about.
WHAT TO WATCH FOR
Forwarding rules nobody created.
WHY
It is the classic sign of a compromised mailbox, and it persists after a password change.
WHAT TO RESTRICT
Automatic forwarding outside the organisation.
WHAT TO ENABLE
Multi-factor authentication for every account, without exception.
WHY
Mail compromise is the commonest incident of all.
