As part of our effort to strengthen email security and protect people from malicious web sites which can lead to stolen credentials and identity theft, we have implemented Advanced Threat Protection (ATP) from Microsoft. ATP has several components which help protect against malicious attacks.
When someone clicks on a URL in an email, Safe Links immediately checks the URL against a database of known malicious sites. If the site is malicious, a warning page is displayed. When hovering over a URL in an email in Outlook that is protected by Safe Links, there is a message that pops up showing the original URL and the instruction to click or tap to follow the link.
When hovering over a URL in Outlook on the web, there is a message that says "Protected by Outlook"
When someone receives an email with an attachment, it is checked in an isolated environment to determine if it contains malware. If malware is detected in the attachment, it is automatically removed. Due to this scanning of the attachments, there can be a minor delay in email delivery (measured in minutes).