diff --git a/cmd/mailfull/command/useradd.go b/cmd/mailfull/command/useradd.go
new file mode 100644
index 0000000..8f3bd1f
--- /dev/null
+++ b/cmd/mailfull/command/useradd.go
@@ -0,0 +1,86 @@
+package command
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/directorz/mailfull-go"
+)
+
+// UserAddCommand represents a UserAddCommand.
+type UserAddCommand struct {
+	Meta
+}
+
+// Synopsis returns a one-line synopsis.
+func (c *UserAddCommand) Synopsis() string {
+	return "Create a new user."
+}
+
+// Help returns long-form help text.
+func (c *UserAddCommand) Help() string {
+	txt := fmt.Sprintf(`
+Usage:
+    %s %s address
+
+Description:
+    %s
+
+Required Args:
+    address
+        The email address that you want to create.
+`,
+		c.CmdName, c.SubCmdName,
+		c.Synopsis())
+
+	return txt[1:]
+}
+
+// Run runs the command and returns the exit status.
+func (c *UserAddCommand) Run(args []string) int {
+	if len(args) != 1 {
+		fmt.Fprintf(c.UI.ErrorWriter, "%v\n", c.Help())
+		return 1
+	}
+
+	address := args[0]
+	words := strings.Split(address, "@")
+	if len(words) != 2 {
+		fmt.Fprintf(c.UI.ErrorWriter, "%v\n", c.Help())
+		return 1
+	}
+
+	userName := words[0]
+	domainName := words[1]
+
+	repo, err := mailfull.OpenRepository(".")
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	user, err := mailfull.NewUser(userName, mailfull.NeverMatchHashedPassword, nil)
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	if err := repo.UserCreate(domainName, user); err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	mailData, err := repo.MailData()
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	err = repo.GenerateDatabases(mailData)
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	return 0
+}
diff --git a/cmd/mailfull/command/userdel.go b/cmd/mailfull/command/userdel.go
new file mode 100644
index 0000000..b19c365
--- /dev/null
+++ b/cmd/mailfull/command/userdel.go
@@ -0,0 +1,80 @@
+package command
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/directorz/mailfull-go"
+)
+
+// UserDelCommand represents a UserDelCommand.
+type UserDelCommand struct {
+	Meta
+}
+
+// Synopsis returns a one-line synopsis.
+func (c *UserDelCommand) Synopsis() string {
+	return "Delete and backup a user."
+}
+
+// Help returns long-form help text.
+func (c *UserDelCommand) Help() string {
+	txt := fmt.Sprintf(`
+Usage:
+    %s %s address
+
+Description:
+    %s
+
+Required Args:
+    address
+        The email address that you want to delete.
+`,
+		c.CmdName, c.SubCmdName,
+		c.Synopsis())
+
+	return txt[1:]
+}
+
+// Run runs the command and returns the exit status.
+func (c *UserDelCommand) Run(args []string) int {
+	if len(args) != 1 {
+		fmt.Fprintf(c.UI.ErrorWriter, "%v\n", c.Help())
+		return 1
+	}
+
+	address := args[0]
+	words := strings.Split(address, "@")
+	if len(words) != 2 {
+		fmt.Fprintf(c.UI.ErrorWriter, "%v\n", c.Help())
+		return 1
+	}
+
+	userName := words[0]
+	domainName := words[1]
+
+	repo, err := mailfull.OpenRepository(".")
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	if err := repo.UserRemove(domainName, userName); err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	mailData, err := repo.MailData()
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	err = repo.GenerateDatabases(mailData)
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	return 0
+}
diff --git a/cmd/mailfull/command/users.go b/cmd/mailfull/command/users.go
new file mode 100644
index 0000000..2f5038d
--- /dev/null
+++ b/cmd/mailfull/command/users.go
@@ -0,0 +1,66 @@
+package command
+
+import (
+	"fmt"
+	"sort"
+
+	"github.com/directorz/mailfull-go"
+)
+
+// UsersCommand represents a UsersCommand.
+type UsersCommand struct {
+	Meta
+}
+
+// Synopsis returns a one-line synopsis.
+func (c *UsersCommand) Synopsis() string {
+	return "Show users."
+}
+
+// Help returns long-form help text.
+func (c *UsersCommand) Help() string {
+	txt := fmt.Sprintf(`
+Usage:
+    %s %s domain
+
+Description:
+    %s
+
+Required Args:
+    domain
+        The domain name.
+`,
+		c.CmdName, c.SubCmdName,
+		c.Synopsis())
+
+	return txt[1:]
+}
+
+// Run runs the command and returns the exit status.
+func (c *UsersCommand) Run(args []string) int {
+	if len(args) != 1 {
+		fmt.Fprintf(c.UI.ErrorWriter, "%v\n", c.Help())
+		return 1
+	}
+
+	targetDomainName := args[0]
+
+	repo, err := mailfull.OpenRepository(".")
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	users, err := repo.Users(targetDomainName)
+	if err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+	sort.Sort(mailfull.UserSlice(users))
+
+	for _, user := range users {
+		fmt.Fprintf(c.UI.Writer, "%s\n", user.Name())
+	}
+
+	return 0
+}
diff --git a/cmd/mailfull/main.go b/cmd/mailfull/main.go
index f67cef6..5f61a5d 100644
--- a/cmd/mailfull/main.go
+++ b/cmd/mailfull/main.go
@@ -67,6 +67,18 @@ func main() {
 			meta.SubCmdName = c.Subcommand()
 			return &command.AliasDomainDelCommand{Meta: meta}, nil
 		},
+		"users": func() (cli.Command, error) {
+			meta.SubCmdName = c.Subcommand()
+			return &command.UsersCommand{Meta: meta}, nil
+		},
+		"useradd": func() (cli.Command, error) {
+			meta.SubCmdName = c.Subcommand()
+			return &command.UserAddCommand{Meta: meta}, nil
+		},
+		"userdel": func() (cli.Command, error) {
+			meta.SubCmdName = c.Subcommand()
+			return &command.UserDelCommand{Meta: meta}, nil
+		},
 		"commit": func() (cli.Command, error) {
 			meta.SubCmdName = c.Subcommand()
 			return &command.CommitCommand{Meta: meta}, nil