A financial services company wants to migrate its email services from on-premises servers to a cloud-based email solution. The Chief information Security Officer (CISO) must brief board of directors on the potential security concerns related to this migration. The board is concerned about the following.

* Transactions being required by unauthorized individual

* Complete discretion regarding client names, account numbers, and investment information.

* Malicious attacker using email to distribute malware and ransom ware.

* Exfiltration of sensitivity company information.

The cloud-based email solution will provide an6-malware, reputation-based scanning, signature-based scanning, and sandboxing. Which of the following is the BEST option to resolve the board’s concerns for this email migration?