Securing Emails After a Security Breach

In today's world, there are unfortunately bad actors which attempt to infiltrate various systems. AI is making this easier then ever, so its important to remain vigilant, however, some of the attack vectors are so convincing that they can fool anyone.
This article will help you re-secure your account if you do become a victim. 
Whilst our focus here is on Microsoft 365 accounts, the principals can be applied to most email providers.
Secure Your Account
Login to your Microsoft Account using your email and password
Select to 
Change Password on the left-hand menu.
Enter a new password, and confirm it.
 
A long password is more secure than a complex password. Consider using a passphrase.
On the 
Security info page, you'll see an option to 
Sign out everywhere. Press this and follow the prompts.
 
This could take up to an hour to be effective.
On the 
Security info page still, remove any devices you do not recognise that are used for MFA (Multi-Factor Authentication).
Check for Email Rules
Often these malicious actors will add in rules to your email inbox to try to hide their activity and to ensure they get the spray to your contacts.
Login to Outlook and navigate to 
Settings > Email > Rules.
In this window you may seem some rules that look out of place, any rules here should be ones you yourself have added so anything that doesn't look right, delete them. For example, a compromised account may have rules that look similar to the below:
Use the 
delete button to restore normal operations. 
Its important to be aware that these rules are not restricted to the example above. It is better to remove any rules you are not sure of as these can be re-added later.
Contacting Affected Recipients
In your Outlook app, review the 
Deleted Items folder - you may find a copy of the phishing email that was sent. You'll then want to:
Reply again to the email
Remove the malicious links
Inform the recipients they link was not from yourself and to not click anything.
Direct them to this page if they require assistance if they have been phished.
Further Support
Contact your email provider if you require further support. Do not delay - its important to move quickly to limit damage potential.