01 March 2023

Understanding your Microsoft 365 email quarantine

The Microsoft 365 “email quarantine” captures incoming spam, phishing, malware and other unwanted email in a secure container. Such emails are locked in the quarantine either until they expire, or you request they be released.

Learn more about malicious emails, phishing, and what to do about them.

We are in the process of reconfiguring the quarantine to capture more regular threats for our iBizify-managed Microsoft 365 clients. We are also working to prevent the delivery of certain file attachment types (such as HTML) that are regularly used to carry phishing attacks.

The side effect of this is that on occasion you may find that some benign email that you did want to receive may not reach your Inbox or even your “Junk mail” folder. To counter this, where there is doubt of the legitimacy of one or more email items, you will receive an email from quarantine@messaging.microsoft.com that look like this:

Microsoft quarantine notification email

The irony isn’t lost on us, that this important message does look like a phishing email. Check that it is indeed from quarantine@messaging.microsoft.com before you click!

In this notice, you can see who sent the quarantined message, when it was sent, and what the subject is.

You have four ways to respond:

1. Ignore it. The quarantined email will be deleted after thirty days.
2. Review Message. If you aren’t sure about it, you can look at the message safely by previewing its contents.
3. The message will be released to your mailbox.
4. Block Sender. In this scope, this option won't actually have any affect because the sender is already blocked from reaching your inbox.

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