Users getting Microsoft Defender for Cloud app notification when external user pings them

Hi All,

We have external access allowed with few domains in our tenant. We noticed that when ever someone from those tenants tries to ping our internal user, the users are getting attached email. The email is coming from MDCA but we don't have any policy configured for this type of incidents.

We also don't have any DLP configured for this.  Any Pointer as to where this alert is getting triggered from will be helpful.

Regards,

Raghav