text: CREATE TABLE mail_template (
  	id         UUID NOT NULL PRIMARY KEY,
  	project_id UUID NOT NULL,
  	mail_type  TEXT NOT NULL,
  	variant    TEXT NOT NULL,
  	subject    TEXT NOT NULL,
  	content    TEXT NOT NULL,
  	use_layout BOOL NOT NULL,
  	CONSTRAINT mail_template_project FOREIGN KEY (project_id) REFERENCES project(id) ON DELETE CASCADE
  );
  
  CREATE UNIQUE INDEX mail_template_identifier ON mail_template(project_id, mail_type, variant);
  CREATE INDEX mail_template_project_index
  	ON mail_template(project_id);
  