Which email delivery option allows clients to manage their own "From" address?

The option that allows clients to manage their own "From" address is the SMTP Relay. This delivery option provides the flexibility needed for clients to set custom "From" addresses when sending emails. By using SMTP Relay, organizations can send emails through their own mail servers or have increased control over email authentication and security.

SMTP Relay is particularly beneficial for businesses that need to maintain brand consistency in their communications, as it allows them to designate a specific email address from which messages are sent. This is essential for building trust with recipients and ensuring that emails do not land in the spam folder.

In contrast, while other options like the Email API and Custom SMTP Server also facilitate email sending, they may impose limitations on the "From" address customization based on the service provider’s configurations. The Direct Mail Service may not focus on advanced features like managing specific "From" addresses, as it typically offers a more standardized email sending process.