diff --git a/internal/endpoint/smtp/session.go b/internal/endpoint/smtp/session.go
index e55d58b7..d44fce4f 100644
--- a/internal/endpoint/smtp/session.go
+++ b/internal/endpoint/smtp/session.go
@@ -107,10 +107,15 @@ func (s *Session) Reset() {
 }
 
 func (s *Session) releaseLimits() {
-	_, domain, err := address.Split(s.mailFrom)
-	if err != nil {
-		return
+	domain := ""
+	if s.mailFrom != "" {
+		var err error
+		_, domain, err = address.Split(s.mailFrom)
+		if err != nil {
+			return
+		}
 	}
+
 	addr, ok := s.msgMeta.Conn.RemoteAddr.(*net.TCPAddr)
 	if !ok {
 		addr = &net.TCPAddr{IP: net.IPv4(127, 0, 0, 1)}