Recipients of Office 365 emails will see links and URLs in the email starting with ''.  The emails have been processed through Outlook's Advanced Threat Protection (ATP) to help protect recipients from malicious sites and threats. 

Safe Links Identification

All links going through Office365 will be scanned by Advanced Threat Protection (ATP). The URL will be scanned and rewritten as shown below.

The URL will change even if the links are safe and will still take you to the desired web page. This URL change applies to emails sent to all recipients.

This website has been classified as 'safe'.

Unsafe Links Identification

The URL will change if the link is unsafe. If you accidentally click on the link, you will see the following: 

This website has been classified as malicious

Safe and Unsafe Attachments Identification

All attachments going through Office365 will be scanned for malware by ATP. If ATP suspects the attachment contains malware, it will still deliver the message but block the attachment.

If an attachment is identified as malicious when scanned, the following message will show:

Notification when an attachment has been detected as 'unsafe'.