Mail settings are defined in the service plan by the mail node. This node is presented by type DomainTemplateMailPreferences (domain_template.xsd). It has the following model:

• The nonexistent-user node is optional. If specified, it is used to collect and handle email messages sent to users whose e-mails the subscription. By default, such messages are sent back to the sender with a message: “this address no longer accepts mail”. To specify the handling method, choose between the following three options:
• The bounce node is used to modify the default rejection message. Data type: string.
• The forward node specifies the email addresses to which undelivered mail should be forwarded. Data type: string.
• The reject node is used to reject such email messages (they will not be accepted by the mail server). Data type: no.
• The webmail node is optional. It specifies whether mail users will be able to read mail through the WebMail application. Contains the name of WebMail application, such as “horde” or “roundcube”. If “none” is specified, the WebMail is not used. Data type: string.
• The maillists node is optional. Switches on or off mailing lists service in a plan. Data type: boolean.
• The mailservice node is optional. Switches on or off mail service in a plan. Data type: boolean.
• The outgoing-messages-mbox-limit node is optional. Specifies the number of email messages per hour that a mailbox is allowed to send. Data type: string.
• The outgoing-messages-domain-limit node is optional. Specifies the number of email messages per hour that all mailboxes under a domain are allowed to send. Data type: string.
• The outgoing-messages-subscription-limit node is optional. Specifies the number of email messages per hour that all mailboxes under a subscription are allowed to send. Data type: string.
• The outgoing-messages-enable-sendmail node is optional. Specifies whether scripts and users are allowed to send email messages (on behalf of the subscription’s system user) by using Sendmail even if the limits on outgoing mail for a mailbox and domain are exceeded. The maximum number of messages that can be sent through Sendmail will be defined by the limit on outgoing mail for an entire subscription. Data type: boolean.
• The outgoing-messages-overlimit-percent node is optional. Specifies the percentage of email messages that should be accepted into the mail queue and whose delivery should be retried the next hour. Data type: integer.

Note that you can also switch on and off mail service in service plans by using the preferences node.