Is Edge SmartScreen blocking Outlook for anyone else?

First pin down the scope: compare affected and unaffected devices, and check whether the same person gets the warning on another device. Note the exact warning text and when it appears. That should help separate a device or browser state from a broader filtering issue.

Before changing any organization-wide policy, check your security logs and current rules for the affected devices. I would avoid turning SmartScreen off broadly just to get around the block.

One reported workaround was clearing browser cookies. It may be worth trying on a single affected device first, especially if the problem seems tied to that machine. Keep in mind that clearing cookies can sign the user out of sites, so it is better as a test than an automatic fix for everyone.

This does not sound universal, since some people report no block at all. I would compare the affected device's browser version, security settings, and network path with a working one, then retest. If the warning persists across devices, collect the details and raise it through your organization's Microsoft support channel rather than adding a broad allow rule right away.