do not perform MX and SMTP checks at all when they are disabled

smtp/server.go

@@ -13,12 +13,20 @@ import (
 	"gitlab.com/etke.cc/postmoogle/utils"
 )
 
-// ErrBanned returned to banned hosts
-var ErrBanned = &smtp.SMTPError{
-	Code:         554,
-	EnhancedCode: smtp.EnhancedCode{5, 5, 4},
-	Message:      "please, don't bother me anymore, kupo.",
-}
+var (
+	// ErrBanned returned to banned hosts
+	ErrBanned = &smtp.SMTPError{
+		Code:         554,
+		EnhancedCode: smtp.EnhancedCode{5, 5, 4},
+		Message:      "please, don't bother me anymore, kupo.",
+	}
+	// ErrNoUser returned when no such mailbox found
+	ErrNoUser = &smtp.SMTPError{
+		Code:         550,
+		EnhancedCode: smtp.EnhancedCode{5, 5, 0},
+		Message:      "no such user here, kupo.",
+	}
+)
 
 type mailServer struct {
 	bot     matrixbot

smtp/session.go

@@ -56,15 +56,13 @@ func (s *incomingSession) Rcpt(to string) error {
 	}
 	if !domainok {
 		s.log.Debug("wrong domain of %s", to)
-		s.ban(s.addr)
-		return ErrBanned
+		return ErrNoUser
 	}
 
 	roomID, ok := s.getRoomID(utils.Mailbox(to))
 	if !ok {
 		s.log.Debug("mapping for %s not found", to)
-		s.ban(s.addr)
-		return ErrBanned
+		return ErrNoUser
 	}
 
 	validations := s.getFilters(roomID)
@@ -166,7 +164,7 @@ func validateEmail(from, to string, log *logger.Logger, options utils.IncomingFi
 	enforce := validator.Enforce{
 		Email: true,
 		MX:    options.SpamcheckMX(),
-		SMTP:  options.SpamcheckMX(),
+		SMTP:  options.SpamcheckSMTP(),
 	}
 	v := validator.New(options.Spamlist(), enforce, to, log)