Hi @Smit Rathod ,
We could not verify the identity of the sender. Click here to get more information. The actual sender of this message is different from the normal sender. Click here to get more information.
According to my research, you get this warning message on Outlook because of the Spoof Intelligence from Microsoft 365 Advanced Threat Protection and Exchange Online Protection.
To resolve this issue, follow the steps below:
In the Microsoft 365 Defender portal at https://security.microsoft.com, go to Email & Collaboration > Policies & Rules > Threat policies > Tenant Allow/Block Lists in the Rules section. To go directly to the Spoofed senders tab on the Tenant Allow/Block List page, use https://security.microsoft.com/tenantAllowBlockList?viewid=SpoofItem.
You can refer to this Microsoft article for more information.