diff --git a/pkg/message/manager.go b/pkg/message/manager.go
index 35d0fcd..b7aba5d 100644
--- a/pkg/message/manager.go
+++ b/pkg/message/manager.go
@@ -35,8 +35,9 @@ type Manager interface {
 
 // StoreManager is a message Manager backed by the storage.Store.
 type StoreManager struct {
-	Store storage.Store
-	Hub   *msghub.Hub
+	AddrPolicy *policy.Addressing
+	Store      storage.Store
+	Hub        *msghub.Hub
 }
 
 // Deliver submits a new message to the store.
@@ -154,7 +155,7 @@ func (s *StoreManager) SourceReader(mailbox, id string) (io.ReadCloser, error) {
 
 // MailboxForAddress parses an email address to return the canonical mailbox name.
 func (s *StoreManager) MailboxForAddress(mailbox string) (string, error) {
-	return policy.ParseMailboxName(mailbox)
+	return s.AddrPolicy.ExtractMailbox(mailbox)
 }
 
 // makeMetadata populates Metadata from a storage.Message.
diff --git a/pkg/policy/address.go b/pkg/policy/address.go
index 25cee9e..be353c0 100644
--- a/pkg/policy/address.go
+++ b/pkg/policy/address.go
@@ -15,13 +15,18 @@ type Addressing struct {
 	Config *config.Root
 }
 
+// ExtractMailbox extracts the mailbox name from a partial email address.
+func (a *Addressing) ExtractMailbox(address string) (string, error) {
+	return parseMailboxName(address)
+}
+
 // NewRecipient parses an address into a Recipient.
 func (a *Addressing) NewRecipient(address string) (*Recipient, error) {
 	local, domain, err := ParseEmailAddress(address)
 	if err != nil {
 		return nil, err
 	}
-	mailbox, err := ParseMailboxName(local)
+	mailbox, err := a.ExtractMailbox(local)
 	if err != nil {
 		return nil, err
 	}
@@ -66,35 +71,6 @@ func (a *Addressing) ShouldStoreDomain(domain string) bool {
 	return false
 }
 
-// ParseMailboxName takes a localPart string (ex: "user+ext" without "@domain")
-// and returns just the mailbox name (ex: "user").  Returns an error if
-// localPart contains invalid characters; it won't accept any that must be
-// quoted according to RFC3696.
-func ParseMailboxName(localPart string) (result string, err error) {
-	if localPart == "" {
-		return "", fmt.Errorf("Mailbox name cannot be empty")
-	}
-	result = strings.ToLower(localPart)
-	invalid := make([]byte, 0, 10)
-	for i := 0; i < len(result); i++ {
-		c := result[i]
-		switch {
-		case 'a' <= c && c <= 'z':
-		case '0' <= c && c <= '9':
-		case bytes.IndexByte([]byte("!#$%&'*+-=/?^_`.{|}~"), c) >= 0:
-		default:
-			invalid = append(invalid, c)
-		}
-	}
-	if len(invalid) > 0 {
-		return "", fmt.Errorf("Mailbox name contained invalid character(s): %q", invalid)
-	}
-	if idx := strings.Index(result, "+"); idx > -1 {
-		result = result[0:idx]
-	}
-	return result, nil
-}
-
 // ParseEmailAddress unescapes an email address, and splits the local part from the domain part.
 // An error is returned if the local or domain parts fail validation following the guidelines
 // in RFC3696.
@@ -263,3 +239,32 @@ func ValidateDomainPart(domain string) bool {
 	}
 	return true
 }
+
+// ParseMailboxName takes a localPart string (ex: "user+ext" without "@domain")
+// and returns just the mailbox name (ex: "user").  Returns an error if
+// localPart contains invalid characters; it won't accept any that must be
+// quoted according to RFC3696.
+func parseMailboxName(localPart string) (result string, err error) {
+	if localPart == "" {
+		return "", fmt.Errorf("Mailbox name cannot be empty")
+	}
+	result = strings.ToLower(localPart)
+	invalid := make([]byte, 0, 10)
+	for i := 0; i < len(result); i++ {
+		c := result[i]
+		switch {
+		case 'a' <= c && c <= 'z':
+		case '0' <= c && c <= '9':
+		case bytes.IndexByte([]byte("!#$%&'*+-=/?^_`.{|}~"), c) >= 0:
+		default:
+			invalid = append(invalid, c)
+		}
+	}
+	if len(invalid) > 0 {
+		return "", fmt.Errorf("Mailbox name contained invalid character(s): %q", invalid)
+	}
+	if idx := strings.Index(result, "+"); idx > -1 {
+		result = result[0:idx]
+	}
+	return result, nil
+}
diff --git a/pkg/policy/address_test.go b/pkg/policy/address_test.go
index 56ae27f..63e5090 100644
--- a/pkg/policy/address_test.go
+++ b/pkg/policy/address_test.go
@@ -122,7 +122,9 @@ func TestShouldStoreDomain(t *testing.T) {
 	}
 }
 
-func TestParseMailboxName(t *testing.T) {
+func TestExtractMailbox(t *testing.T) {
+	addrPolicy := policy.Addressing{Config: &config.Root{}}
+
 	var validTable = []struct {
 		input  string
 		expect string
@@ -139,7 +141,7 @@ func TestParseMailboxName(t *testing.T) {
 		{"chars|}~", "chars|}~"},
 	}
 	for _, tt := range validTable {
-		if result, err := policy.ParseMailboxName(tt.input); err != nil {
+		if result, err := addrPolicy.ExtractMailbox(tt.input); err != nil {
 			t.Errorf("Error while parsing %q: %v", tt.input, err)
 		} else {
 			if result != tt.expect {
@@ -157,7 +159,7 @@ func TestParseMailboxName(t *testing.T) {
 		{"first\nlast", "Control chars not permitted"},
 	}
 	for _, tt := range invalidTable {
-		if _, err := policy.ParseMailboxName(tt.input); err == nil {
+		if _, err := addrPolicy.ExtractMailbox(tt.input); err == nil {
 			t.Errorf("Didn't get an error while parsing %q: %v", tt.input, tt.msg)
 		}
 	}
diff --git a/pkg/storage/file/fstore.go b/pkg/storage/file/fstore.go
index b31ea0f..a52bc36 100644
--- a/pkg/storage/file/fstore.go
+++ b/pkg/storage/file/fstore.go
@@ -10,7 +10,6 @@ import (
 	"time"
 
 	"github.com/jhillyerd/inbucket/pkg/config"
-	"github.com/jhillyerd/inbucket/pkg/policy"
 	"github.com/jhillyerd/inbucket/pkg/storage"
 	"github.com/jhillyerd/inbucket/pkg/stringutil"
 	"github.com/rs/zerolog/log"
@@ -66,10 +65,7 @@ func New(cfg config.Storage) (storage.Store, error) {
 
 // AddMessage adds a message to the specified mailbox.
 func (fs *Store) AddMessage(m storage.Message) (id string, err error) {
-	mb, err := fs.mbox(m.Mailbox())
-	if err != nil {
-		return "", err
-	}
+	mb := fs.mbox(m.Mailbox())
 	mb.Lock()
 	defer mb.Unlock()
 	r, err := m.Source()
@@ -127,10 +123,7 @@ func (fs *Store) AddMessage(m storage.Message) (id string, err error) {
 
 // GetMessage returns the messages in the named mailbox, or an error.
 func (fs *Store) GetMessage(mailbox, id string) (storage.Message, error) {
-	mb, err := fs.mbox(mailbox)
-	if err != nil {
-		return nil, err
-	}
+	mb := fs.mbox(mailbox)
 	mb.RLock()
 	defer mb.RUnlock()
 	return mb.getMessage(id)
@@ -138,10 +131,7 @@ func (fs *Store) GetMessage(mailbox, id string) (storage.Message, error) {
 
 // GetMessages returns the messages in the named mailbox, or an error.
 func (fs *Store) GetMessages(mailbox string) ([]storage.Message, error) {
-	mb, err := fs.mbox(mailbox)
-	if err != nil {
-		return nil, err
-	}
+	mb := fs.mbox(mailbox)
 	mb.RLock()
 	defer mb.RUnlock()
 	return mb.getMessages()
@@ -149,10 +139,7 @@ func (fs *Store) GetMessages(mailbox string) ([]storage.Message, error) {
 
 // MarkSeen flags the message as having been read.
 func (fs *Store) MarkSeen(mailbox, id string) error {
-	mb, err := fs.mbox(mailbox)
-	if err != nil {
-		return err
-	}
+	mb := fs.mbox(mailbox)
 	mb.Lock()
 	defer mb.Unlock()
 	if !mb.indexLoaded {
@@ -175,10 +162,7 @@ func (fs *Store) MarkSeen(mailbox, id string) error {
 
 // RemoveMessage deletes a message by ID from the specified mailbox.
 func (fs *Store) RemoveMessage(mailbox, id string) error {
-	mb, err := fs.mbox(mailbox)
-	if err != nil {
-		return err
-	}
+	mb := fs.mbox(mailbox)
 	mb.Lock()
 	defer mb.Unlock()
 	return mb.removeMessage(id)
@@ -186,10 +170,7 @@ func (fs *Store) RemoveMessage(mailbox, id string) error {
 
 // PurgeMessages deletes all messages in the named mailbox, or returns an error.
 func (fs *Store) PurgeMessages(mailbox string) error {
-	mb, err := fs.mbox(mailbox)
-	if err != nil {
-		return err
-	}
+	mb := fs.mbox(mailbox)
 	mb.Lock()
 	defer mb.Unlock()
 	return mb.purge()
@@ -241,12 +222,8 @@ func (fs *Store) VisitMailboxes(f func([]storage.Message) (cont bool)) error {
 }
 
 // mbox returns the named mailbox.
-func (fs *Store) mbox(mailbox string) (*mbox, error) {
-	name, err := policy.ParseMailboxName(mailbox)
-	if err != nil {
-		return nil, err
-	}
-	hash := stringutil.HashMailboxName(name)
+func (fs *Store) mbox(mailbox string) *mbox {
+	hash := stringutil.HashMailboxName(mailbox)
 	s1 := hash[0:3]
 	s2 := hash[0:6]
 	path := filepath.Join(fs.mailPath, s1, s2, hash)
@@ -254,11 +231,11 @@ func (fs *Store) mbox(mailbox string) (*mbox, error) {
 	return &mbox{
 		RWMutex:   fs.hashLock.Get(hash),
 		store:     fs,
-		name:      name,
+		name:      mailbox,
 		dirName:   hash,
 		path:      path,
 		indexPath: indexPath,
-	}, nil
+	}
 }
 
 // mboxFromPath constructs a mailbox based on name hash.
diff --git a/pkg/test/manager.go b/pkg/test/manager.go
index f5053df..d719eb9 100644
--- a/pkg/test/manager.go
+++ b/pkg/test/manager.go
@@ -3,6 +3,7 @@ package test
 import (
 	"errors"
 
+	"github.com/jhillyerd/inbucket/pkg/config"
 	"github.com/jhillyerd/inbucket/pkg/message"
 	"github.com/jhillyerd/inbucket/pkg/policy"
 	"github.com/jhillyerd/inbucket/pkg/storage"
@@ -55,7 +56,8 @@ func (m *ManagerStub) GetMetadata(mailbox string) ([]*message.Metadata, error) {
 
 // MailboxForAddress invokes policy.ParseMailboxName.
 func (m *ManagerStub) MailboxForAddress(address string) (string, error) {
-	return policy.ParseMailboxName(address)
+	addrPolicy := &policy.Addressing{Config: &config.Root{}}
+	return addrPolicy.ExtractMailbox(address)
 }
 
 // MarkSeen marks a message as having been read.