https://wiki.zimbra.com/wiki/Ajcody-How-To-Setup-sendAs-Right-And-Persona-For-Internal-Users

Use the Zimbra Admin 'gear icon' to show options.

1. Configure → Domains → Add a Domain Alias (if any)
2. Manage → Accounts → Aliases → Add → Save
3. Manage → Accounts → General → Edit Account → Delegated Authority → Address Delegation → Allow → Save

To grant the right to a user account:

su - zimbra
zmprov grr dl list@example.tld usr user@example.tld sendAsDistList

To revoke the right:

su - zimbra
zmprov rvr dl list@example.tld usr user@example.tld sendAsDistList

Logged into the ZWC as the user, add the distribution list Persona:

ZWC → Preferences → Add Persona

1. Edit the name label of the Persona
2. Edit the From text
3. Select the Distribution List address as the From address
4. Click Save

User Account Preferences