Large file attachments will be sent as a securedoc attachment. This means that the recipient will receive an encrypted message with a securedoc.html attachment that contains a link to download the large file from the Cisco Secure Email Encryption Service portal[2, p. 9].
This feature can only be enabled if the Read from Message feature is enabled. The Read from Message feature allows you to encrypt messages based on keywords or phrases in the subject or body of the message. You need to enable this feature before you can enable the large file attachments feature[2, p. 8].
The other options are not valid because:
A) Large file attachments can be sent using both the websafe portal and the Cisco Secure Email Add-In. The websafe portal allows you to compose and send encrypted messages from any web browser, while the Cisco Secure Email Add-In allows you to encrypt messages from your email client such as Outlook[2, p. 6-7].
B) This feature allows users to send up to 100MB of attachments in a secure email, not 50MB[2, p. 9].
D) Large file attachments can be sent using both the websafe portal and the Cisco Secure Email Add-In. The websafe portal allows you to compose and send encrypted messages from any web browser, while the Cisco Secure Email Add-In allows you to encrypt messages from your email client such as Outlook[2, p. 6-7].