Mailing settings are defined in the domain template by the mail node. This node is presented by type MailPreferences (plesk_mailname.xsd). It has the following graphics model:

The nonexistent-user node is optional. If specified, it is used to collect and handle messages sent to email users not registered on the domain. 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 webmail node is optional. It specifies whether mail users will be able to read mail through the WebMail application. Data type: boolean.