diff --git a/go.mod b/go.mod
index a4ef76f..a49542e 100644
--- a/go.mod
+++ b/go.mod
@@ -10,8 +10,8 @@ require (
 	github.com/emersion/go-imap v1.2.1
 	github.com/emersion/go-mbox v1.0.3
 	github.com/emersion/go-message v0.16.0
-	github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac // indirect
-	github.com/emersion/go-smtp v0.15.0
+	github.com/emersion/go-sasl v0.0.0-20220912192320-0145f2c60ead // indirect
+	github.com/emersion/go-smtp v0.18.0
 	github.com/emersion/go-vcard v0.0.0-20220507122617-d4056df0ec4a
 	github.com/emersion/go-webdav v0.3.2-0.20220524091811-5d845721d8f7
 	golang.org/x/crypto v0.0.0-20220817201139-bc19a97f63c8
diff --git a/go.sum b/go.sum
index 3eb505e..2f0b044 100644
--- a/go.sum
+++ b/go.sum
@@ -18,10 +18,10 @@ github.com/emersion/go-message v0.15.0/go.mod h1:wQUEfE+38+7EW8p8aZ96ptg6bAb1iwd
 github.com/emersion/go-message v0.16.0 h1:uZLz8ClLv3V5fSFF/fFdW9jXjrZkXIpE1Fn8fKx7pO4=
 github.com/emersion/go-message v0.16.0/go.mod h1:pDJDgf/xeUIF+eicT6B/hPX/ZbEorKkUMPOxrPVG2eQ=
 github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
-github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac h1:tn/OQ2PmwQ0XFVgAHfjlLyqMewry25Rz7jWnVoh4Ggs=
-github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
-github.com/emersion/go-smtp v0.15.0 h1:3+hMGMGrqP/lqd7qoxZc1hTU8LY8gHV9RFGWlqSDmP8=
-github.com/emersion/go-smtp v0.15.0/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
+github.com/emersion/go-sasl v0.0.0-20220912192320-0145f2c60ead h1:fI1Jck0vUrXT8bnphprS1EoVRe2Q5CKCX8iDlpqjQ/Y=
+github.com/emersion/go-sasl v0.0.0-20220912192320-0145f2c60ead/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
+github.com/emersion/go-smtp v0.18.0 h1:lrVQqB0JdxYjC8CsBt55pSwB756bRRN6vK0DSr0pXfM=
+github.com/emersion/go-smtp v0.18.0/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
 github.com/emersion/go-textwrapper v0.0.0-20200911093747-65d896831594 h1:IbFBtwoTQyw0fIM5xv1HF+Y+3ZijDR839WMulgxCcUY=
 github.com/emersion/go-textwrapper v0.0.0-20200911093747-65d896831594/go.mod h1:aqO8z8wPrjkscevZJFVE1wXJrLpC5LtJG7fqLOsPb2U=
 github.com/emersion/go-vcard v0.0.0-20191221110513-5f81fa0d3cc7/go.mod h1:HMJKR5wlh/ziNp+sHEDV2ltblO4JD2+IdDOWtGcQBTM=
diff --git a/smtp/smtp.go b/smtp/smtp.go
index 69caddd..6df1006 100644
--- a/smtp/smtp.go
+++ b/smtp/smtp.go
@@ -367,29 +367,64 @@ func SendMail(c *protonmail.Client, u *protonmail.User, privateKeys openpgp.Enti
 }
 
 type session struct {
-	c            *protonmail.Client
-	u            *protonmail.User
-	privateKeys  openpgp.EntityList
-	addrs        []*protonmail.Address
+	be *backend
+
+	c           *protonmail.Client
+	u           *protonmail.User
+	privateKeys openpgp.EntityList
+	addrs       []*protonmail.Address
+
 	allReceivers []string
 }
 
-func (s *session) Mail(from string, options smtp.MailOptions) error {
+func (s *session) AuthPlain(username, password string) error {
+	c, privateKeys, err := s.be.sessions.Auth(username, password)
+	if err != nil {
+		return err
+	}
+
+	u, err := c.GetCurrentUser()
+	if err != nil {
+		return err
+	}
+
+	addrs, err := c.ListAddresses()
+	if err != nil {
+		return err
+	}
+
+	// TODO: decrypt private keys in u.Addresses
+
+	log.Printf("%s logged in", username)
+	s.c = c
+	s.u = u
+	s.privateKeys = privateKeys
+	s.addrs = addrs
 	return nil
 }
 
-func (s *session) Rcpt(to string) error {
+func (s *session) Mail(from string, options *smtp.MailOptions) error {
+	if s.c == nil {
+		return smtp.ErrAuthRequired
+	}
+	return nil
+}
+
+func (s *session) Rcpt(to string, options *smtp.RcptOptions) error {
+	if s.c == nil {
+		return smtp.ErrAuthRequired
+	}
 	if to == "" {
 		return nil
 	}
-
-	// Seems like github.com/emersion/go-smtp/conn.go:487 removes marks on message
-	// "to" is added into allReceivers blindly
 	s.allReceivers = append(s.allReceivers, to)
 	return nil
 }
 
 func (s *session) Data(r io.Reader) error {
+	if s.c == nil {
+		return smtp.ErrAuthRequired
+	}
 	return SendMail(s.c, s.u, s.privateKeys, s.addrs, s.allReceivers, r)
 }
 
@@ -398,10 +433,7 @@ func (s *session) Reset() {
 }
 
 func (s *session) Logout() error {
-	s.c = nil
-	s.u = nil
-	s.privateKeys = nil
-	s.allReceivers = nil
+	*s = session{be: s.be}
 	return nil
 }
 
@@ -409,36 +441,8 @@ type backend struct {
 	sessions *auth.Manager
 }
 
-func (be *backend) Login(_ *smtp.ConnectionState, username, password string) (smtp.Session, error) {
-	c, privateKeys, err := be.sessions.Auth(username, password)
-	if err != nil {
-		return nil, err
-	}
-
-	u, err := c.GetCurrentUser()
-	if err != nil {
-		return nil, err
-	}
-
-	addrs, err := c.ListAddresses()
-	if err != nil {
-		return nil, err
-	}
-
-	// TODO: decrypt private keys in u.Addresses
-
-	log.Printf("%s logged in", username)
-
-	return &session{
-		c:           c,
-		u:           u,
-		privateKeys: privateKeys,
-		addrs:       addrs,
-	}, nil
-}
-
-func (be *backend) AnonymousLogin(_ *smtp.ConnectionState) (smtp.Session, error) {
-	return nil, smtp.ErrAuthRequired
+func (be *backend) NewSession(_ *smtp.Conn) (smtp.Session, error) {
+	return &session{be: be}, nil
 }
 
 func New(sessions *auth.Manager) smtp.Backend {