diff --git a/src/sendmail/mod.rs b/src/sendmail/mod.rs
index abedd90..89b2ae7 100644
--- a/src/sendmail/mod.rs
+++ b/src/sendmail/mod.rs
@@ -69,6 +69,7 @@ impl<'a> Transport<'a> for SendmailTransport {
                 .arg("-i")
                 .arg("-f")
                 .arg(from)
+                .arg("--")
                 .args(to)
                 .stdin(Stdio::piped())
                 .stdout(Stdio::piped())