diff --git a/backend.go b/backend.go
index 97599df..e2af9af 100644
--- a/backend.go
+++ b/backend.go
@@ -21,9 +21,20 @@ type Backend interface {
 	AnonymousLogin(state *ConnectionState) (Session, error)
 }
 
+type BodyType string
+
+const (
+	Body7Bit       BodyType = "7BIT"
+	Body8BitMIME   BodyType = "8BITMIME"
+	BodyBinaryMIME BodyType = "BINARYMIME"
+)
+
 // MailOptions contains custom arguments that were
 // passed as an argument to the MAIL command.
 type MailOptions struct {
+	// Value of BODY= argument, 7BIT, 8BITMIME or BINARYMIME.
+	Body BodyType
+
 	// Size of the body. Can be 0 if not specified by client.
 	Size int
 
diff --git a/conn.go b/conn.go
index b7be1f4..87db096 100644
--- a/conn.go
+++ b/conn.go
@@ -260,6 +260,9 @@ func (c *Conn) handleGreet(enhanced bool, arg string) {
 		if _, isTLS := c.TLSConnectionState(); isTLS && c.server.EnableREQUIRETLS {
 			caps = append(caps, "REQUIRETLS")
 		}
+		if c.server.EnableBINARYMIME {
+			caps = append(caps, "BINARYMIME")
+		}
 		if c.server.MaxMessageBytes > 0 {
 			caps = append(caps, fmt.Sprintf("SIZE %v", c.server.MaxMessageBytes))
 		}
@@ -350,11 +353,17 @@ func (c *Conn) handleMail(arg string) {
 				opts.RequireTLS = true
 			case "BODY":
 				switch value {
+				case "BINARYMIME":
+					if !c.server.EnableBINARYMIME {
+						c.WriteResponse(504, EnhancedCode{5, 5, 4}, "BINARYMIME is not implemented")
+						return
+					}
 				case "7BIT", "8BITMIME":
 				default:
 					c.WriteResponse(500, EnhancedCode{5, 5, 4}, "Unknown BODY value")
 					return
 				}
+				opts.Body = BodyType(value)
 			case "AUTH":
 				value, err := decodeXtext(value)
 				if err != nil {
diff --git a/server.go b/server.go
index 2632d39..4fa0b95 100755
--- a/server.go
+++ b/server.go
@@ -53,6 +53,10 @@ type Server struct {
 	// Should be used only if backend supports it.
 	EnableREQUIRETLS bool
 
+	// Advertise BINARYMIME (RFC 3030) capability.
+	// Should be used only if backend supports it.
+	EnableBINARYMIME bool
+
 	// If set, the AUTH command will not be advertised and authentication
 	// attempts will be rejected. This setting overrides AllowInsecureAuth.
 	AuthDisabled bool
diff --git a/server_test.go b/server_test.go
index fea010a..48ad654 100644
--- a/server_test.go
+++ b/server_test.go
@@ -1045,3 +1045,51 @@ func TestServer_Chunking_tooLongMessage(t *testing.T) {
 		t.Fatal("Invalid number of sent messages:", be.messages, be.anonmsgs)
 	}
 }
+
+func TestServer_Chunking_Binarymime(t *testing.T) {
+	be, s, c, scanner := testServerAuthenticated(t)
+	defer s.Close()
+	defer c.Close()
+	s.EnableBINARYMIME = true
+
+	io.WriteString(c, "MAIL FROM:<root@nsa.gov> BODY=BINARYMIME\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid MAIL response:", scanner.Text())
+	}
+
+	io.WriteString(c, "RCPT TO:<root@gchq.gov.uk>\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid RCPT response:", scanner.Text())
+	}
+
+	io.WriteString(c, "BDAT 8\r\n")
+	io.WriteString(c, "Hey <3\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid BDAT response:", scanner.Text())
+	}
+
+	io.WriteString(c, "BDAT 8 LAST\r\n")
+	io.WriteString(c, "Hey :3\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid BDAT response:", scanner.Text())
+	}
+
+	if len(be.messages) != 1 || len(be.anonmsgs) != 0 {
+		t.Fatal("Invalid number of sent messages:", be.messages, be.anonmsgs)
+	}
+
+	msg := be.messages[0]
+	if msg.From != "root@nsa.gov" {
+		t.Fatal("Invalid mail sender:", msg.From)
+	}
+	if len(msg.To) != 1 || msg.To[0] != "root@gchq.gov.uk" {
+		t.Fatal("Invalid mail recipients:", msg.To)
+	}
+	if want := "Hey <3\r\nHey :3\r\n"; string(msg.Data) != want {
+		t.Fatal("Invalid mail data:", string(msg.Data), msg.Data)
+	}
+}
diff --git a/smtp.go b/smtp.go
index e5045a7..77ef835 100644
--- a/smtp.go
+++ b/smtp.go
@@ -8,6 +8,8 @@
 //	ENHANCEDSTATUSCODES	RFC 2034
 //  SMTPUTF8		RFC 6531
 //  REQUIRETLS		draft-ietf-uta-smtp-require-tls-09
+//  CHUNKING		RFC 3030
+//  BINARYMIME		RFC 3030
 //
 // LMTP (RFC 2033) is also supported.
 //