diff --git a/app/src/main/java/eu/faircode/email/MessageHelper.java b/app/src/main/java/eu/faircode/email/MessageHelper.java
index caad678c85..4312f4f8cc 100644
--- a/app/src/main/java/eu/faircode/email/MessageHelper.java
+++ b/app/src/main/java/eu/faircode/email/MessageHelper.java
@@ -3181,6 +3181,8 @@ public class MessageHelper {
             String by = kv.get("by").toString();
             if (by.matches(".*\\.google\\.com"))
                 return true;
+            if (by.toLowerCase(Locale.ROOT).contains("sendmail"))
+                return true;
             if (by.startsWith("filterdrecv-"))
                 return true;
             if (isLocal(by)) {