Safe Links is a component of Microsoft’s Advanced Threat Protection.
ATP Safe Links can help protect your organization by providing time-of-click verification of web addresses (URLs) in email messages and Office documents.
Time-of-click verification is achieved by re-writing the Link behind the text to force it to be checked by Microsoft’s Proxy service in the cloud each time the link is accessed. This means if the link is valid when you receive the email but later is hijacked or compromised the user will be warned or blocked.
Here’s what the link would look like in action when a mouse hovers over a link in an email:
Protection is defined through policies that are set by your Office 365 security team.
With ATP Safe Links policies in place, Office 365 administrators can view reports for Advanced Threat Protection. The information in those reports can help further protect your organization.
If you are blocked from accessing a page that’s valid or required in your role you should raise this with your manager who should then raise a ticket on your IT Support team so that this may be reviewed and discussed.