To manage the templates that the system uses when creating email alerts, you can use the manage-email command of the cell management tool.

By default, the system sends email alerts that notify system administrators of events and conditions that are likely to require their intervention. The list of email recipients can be updated using the VMware Cloud Director API or the Web console. You can override the default email content for each kind of alert by using a cell management tool command line of the following form: 
cell-management-tool manage-email  options
Table 1. Cell Management Tool Options and Arguments, manage-email Subcommand
Option Argument Description
--help None Provides a summary of available commands in this category.
--delete template name The name of the template to delete.
--lookup template name This argument is optional. If you do not supply it, the command returns a list of all template names.
--locale the template locale By default, this command operates on templates in the en-US locale. To specify a different locale, use this option.
--set-template path name to a file containing an updated email template This file must be accessible on the local host and readable by the user vcloud.vcloud. For example, /tmp/my-email-template.txt

There are different allowed template names that you can use for different email notifications.

Table 2. VMware Cloud Director Email Notification Names
Name Description When the email is sent Recipients
VAPP_UNDEPLOY_NOTIFICATION_SUBJECT Alert when the vApp runtime lease is about to expire. When the lease expires, VMware Cloud Director suspends or powers off the vApp. Before the runtime lease of a vApp expires, depending on the configured deployment and storage lease alert time. The owner of the vApp, or if the owner is a system administrator, the organization administrators receive the notification.
VAPP_UNDEPLOY_NOTIFICATION_BODY
VAPP_STORAGE_NOTIFICATION_DELETE_SUBJECT Alert when the vApp storage lease is about to expire. When the lease expires, VMware Cloud Director deletes the vApp. Before the storage lease of a vApp expires, depending on the configured deployment and storage lease alert time. The owner of the vApp, or if the owner is a system administrator, the organization administrators receive the notification.
VAPP_STORAGE_NOTIFICATION_BODY
VAPP_STORAGE_NOTIFICATION_FLAG_SUBJECT Alert when the vApp storage lease is about to expire. When the lease expires, VMware Cloud Director marks the vApp as expired. Before the storage lease of a vApp expires, depending on the configured deployment and storage lease alert time. The owner of the vApp, or if the owner is a system administrator, the organization administrators receive the notification.
VAPP_STORAGE_NOTIFICATION_BODY
VAPPTEMPLATE_STORAGE_NOTIFICATION_DELETE_SUBJECT Alert when the vApp template storage lease is about to expire. When the lease expires, VMware Cloud Director deletes the vApp template. Before the storage lease of a vApp template expires, depending on the configured deployment and storage lease alert time. The owner of the vApp Template, or if the owner is a system administrator, the organization administrators receive the notification.
VAPPTEMPLATE_STORAGE_NOTIFICATION_BODY
VAPPTEMPLATE_STORAGE_NOTIFICATION_FLAG_SUBJECT Alert when the vApp template storage lease is about to expire. When the lease expires, VMware Cloud Director marks the vApp template as expired. Before the storage lease of a vApp template expires, depending on the configured deployment and storage lease alert time. The owner of the vApp Template, or if the owner is a system administrator, the organization administrators receive the notification.
VAPPTEMPLATE_STORAGE_NOTIFICATION_BODY
DISK_STORAGE_ALERT Disk Storage Alert (Red Alert) When there is low disk space on the datastore and it reaches the red threshold. System administrators
DISK_STORAGE_ALERT_VDCS Disk storage alert to provider VDCs. The email contains the list provider VDCs using the datastore that has a red alert due to low hard disk space. When there is low disk space on the datastore and it reaches the red threshold. System administrators
VM_HW_UPGRADE_INVALID_POWER_STATE A notification about the power state of a VM. To upgrade the virtual hardware, you must power off the VM. When a user attempts to upgrade the hardware version of a VM. The owner of the VM, or if the owner is a system administrator, the organization administrators receive the notification.
VM_UPDATE_NESTED_HV_INVALID_POWER_STATE
FEDERATION_CERTIFICATE_SUCCESS_SUBJECT Federation certificate expiration notification sent to all organization administrators when a certificate for an external SSO server is about to expire. It prompts the organization administrators to download a new certificate from the SSO server and update VMware Cloud Director. If a federation certificate expires within 7 days from the current date. Organization administrators
FEDERATION_CERTIFICATE_SUCCESS_BODY
IPSEC_VPN_TUNNEL_ERROR VPN tunnel Error (Red Alert) When the VPN tunnel is not operational. System administrators
IPSEC_VPN_TUNNEL_ERROR_SUMMARY
IPSEC_VPN_TUNNEL_ENABLED VPN tunnel Enabled (Green Alert) When the VPN tunnel is working again after not being operational. System administrators
IPSEC_VPN_TUNNEL_ENABLED _SUMMARY
Table 3. Non-customizable Email Templates
Notification When the email is sent Recipients
Reconnected vCenter Server email alert When a vCenter Server is reconnected. System administrators
Disconnected vCenter Server email alert. The email states whether an error or a user request caused the disconnecting of the vCenter Server. When a vCenter Server is disconnected. System administrators
AMQP Connection Lost email alert. Alert notifying that VMware Cloud Director is disconnected from the AMQP Server. When the RabbitMQ stops working. System administrators
Broken Database Connection email alert When VMware Cloud Director is disconnected from the database. System administrators
Restored Database Connection email alert When VMware Cloud Director is reconnected to the database. System administrators
Host Disconnected from Switch email alert When a host gets disconnected from the available switches. System administrators
Host Disconnected from Distributed Virtual Switch email alert When a host gets disconnected from the available distributed virtual switches. System administrators
LDAP Error email alert During the synchronization with LDAP. System administrators
LDAP User Sync email alert During the renaming of an LDAP user. System administrators
Site Associations Status Change email alert The sites recently lost connection, regained connection, or are still down. System administrators

Update an Email Template

The following command replaces the current contents of the DISK_STORAGE_ALERT_VDCS email template with content you created in a file named /tmp/DISK_STORAGE_ALERT_VDCS-new.txt. 
[root@cell1 /opt/vmware/vcloud-director/bin]#./cell-management-tool manage-email --set-template DISK_STORAGE_ALERT_VDCS /tmp/DISK_STORAGE_ALERT_VDCS-new.txt

New property being stored: Property "email.template.DISK_STORAGE_ALERT_VDCS.en-US" has value 
"This is an alert from $productName The $datastore is used by the following PVDC(s): $pvdcsList
"
Property "email.template.DISK_STORAGE_ALERT_VDCS.en-US" has value "This is an alert from $productName The $datastore is used by the followingProvider VDC(s): $pvdcsList
"

VCD Email notification details:
 name                     : DISK_STORAGE_ALERT_VDCS
 description              : Alert when used disk storage exceeds threshold
 config key               : email.template.DISK_STORAGE_ALERT_VDCS.en-US
 template placeholders    : [productName, storageContainerType, datastore, percentage, currentFreeSpaceMB, diskSizeBytes, pvdcsList]
 template content         : This is an alert from $productName The $datastore is used by the followingProvider VDC(s): $pvdcsList