diff --git a/webmail/api.go b/webmail/api.go
index 82f854a..8479e02 100644
--- a/webmail/api.go
+++ b/webmail/api.go
@@ -1417,12 +1417,28 @@ func addressString(a message.Address, smtputf8 bool) string {
 			host = dom.ASCII
 		}
 	}
-	s := "<" + a.User + "@" + host + ">"
-	if a.Name != "" {
-		// todo: properly encoded/escaped name
-		s = a.Name + " " + s
+	if a.Name == "" {
+		return "<" + a.User + "@" + host + ">"
 	}
-	return s
+	// We only quote the name if we have to. ../rfc/5322:679
+	const atom = "!#$%&'*+-/=?^_`{|}~"
+	name := a.Name
+	for _, c := range a.Name {
+		if c == '\t' || c == ' ' || c >= 0x80 || c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' || strings.ContainsAny(string(c), atom) {
+			continue
+		}
+		// We need to quote.
+		q := `"`
+		for _, c := range a.Name {
+			if c == '\\' || c == '"' {
+				q += `\`
+			}
+			q += string(c)
+		}
+		q += `"`
+		name = q
+	}
+	return name + " <" + a.User + "@" + host + ">"
 }
 
 // MailboxSetSpecialUse sets the special use flags of a mailbox.
diff --git a/webmail/api_test.go b/webmail/api_test.go
index 7276905..171af43 100644
--- a/webmail/api_test.go
+++ b/webmail/api_test.go
@@ -315,7 +315,7 @@ func TestAPI(t *testing.T) {
 	draftID := api.MessageCompose(ctx, ComposeMessage{
 		From:     "mjl@mox.example",
 		To:       []string{"mjl+to@mox.example", "mjl to2 <mjl+to2@mox.example>"},
-		Cc:       []string{"mjl+cc@mox.example", "mjl cc2 <mjl+cc2@mox.example>"},
+		Cc:       []string{"mjl+cc@mox.example", `"mjl, cc2" <mjl+cc2@mox.example>`},
 		Bcc:      []string{"mjl+bcc@mox.example", "mjl bcc2 <mjl+bcc2@mox.example>"},
 		Subject:  "test email",
 		TextBody: "this is the content\n\ncheers,\nmox",
@@ -325,7 +325,7 @@ func TestAPI(t *testing.T) {
 	draftID = api.MessageCompose(ctx, ComposeMessage{
 		From:           "mjl@mox.example",
 		To:             []string{"mjl+to@mox.example", "mjl to2 <mjl+to2@mox.example>"},
-		Cc:             []string{"mjl+cc@mox.example", "mjl cc2 <mjl+cc2@mox.example>"},
+		Cc:             []string{"mjl+cc@mox.example", `"mjl, cc2" <mjl+cc2@mox.example>`},
 		Bcc:            []string{"mjl+bcc@mox.example", "mjl bcc2 <mjl+bcc2@mox.example>"},
 		Subject:        "test email",
 		TextBody:       "this is the content\n\ncheers,\nmox",
@@ -345,7 +345,7 @@ func TestAPI(t *testing.T) {
 	api.MessageSubmit(ctx, SubmitMessage{
 		From:           "mjl@mox.example",
 		To:             []string{"mjl+to@mox.example", "mjl to2 <mjl+to2@mox.example>"},
-		Cc:             []string{"mjl+cc@mox.example", "mjl cc2 <mjl+cc2@mox.example>"},
+		Cc:             []string{"mjl+cc@mox.example", `"mjl, cc2" <mjl+cc2@mox.example>`},
 		Bcc:            []string{"mjl+bcc@mox.example", "mjl bcc2 <mjl+bcc2@mox.example>"},
 		Subject:        "test email",
 		TextBody:       "this is the content\n\ncheers,\nmox",
@@ -358,7 +358,7 @@ func TestAPI(t *testing.T) {
 	api.MessageSubmit(ctx, SubmitMessage{
 		From:      "mjl-altcatchall@mox.example",
 		To:        []string{"mjl-to@mox.example", "mjl to2 <mjl+to2@mox.example>"},
-		Cc:        []string{"mjl-cc@mox.example", "mjl cc2 <mjl+cc2@mox.example>"},
+		Cc:        []string{"mjl-cc@mox.example", `"mjl, cc2" <mjl+cc2@mox.example>`},
 		Bcc:       []string{"mjl-bcc@mox.example", "mjl bcc2 <mjl+bcc2@mox.example>"},
 		Subject:   "test email",
 		TextBody:  "this is the content\n\ncheers,\nmox",
@@ -511,7 +511,7 @@ func TestAPI(t *testing.T) {
 	tcompare(t, len(l), 0)
 	tcompare(t, full, true)
 	l, full = api.CompleteRecipient(ctx, "cc2")
-	tcompare(t, l, []string{"mjl cc2 <mjl+cc2@mox.example>", "mjl bcc2 <mjl+bcc2@mox.example>"})
+	tcompare(t, l, []string{`"mjl, cc2" <mjl+cc2@mox.example>`, "mjl bcc2 <mjl+bcc2@mox.example>"})
 	tcompare(t, full, true)
 
 	// RecipientSecurity