How to Schedule emails for future delivery in Zimbra

You can enable mail delivery schedule option in Zimbra mail server by modifying in COS features.

Enable from CLI
$ zmprov mc COS_name zimbraFeatureMailSendLaterEnabled TRUE
Example;
$ zmprov mc default zimbraFeatureMailSendLaterEnabled TRUE

Check  zimbraFeatureMailSendLaterEnabled enabled status
$ zmprov gc default| grep -i zimbraFeatureMailSendLaterEnabled
zimbraFeatureMailSendLaterEnabled: TRUE


Enable from GUI
Login to Admin Panale  > Configure > Class of Service (Edit Class of service on which you want to apply settings )

Now login with Webmail account and follow the steps
Compose new mail > Click on send dropdown arrow  > Send Later