--- arpwatch-3.8/report.c~	2025-09-20 13:57:16.351246657 +0000
+++ arpwatch-3.8/report.c	2025-09-20 13:43:47.777995101 +0000
@@ -390,7 +390,7 @@
 	close(fd);
 
 	/* Always Deliver interactively (pause when child depth gets large) */
-	execl(sendmail, "sendmail", "-odi", watcher, NULL);
+	execl(sendmail, "sendmail", "-odi", watcher, "-f", watchee, NULL);
 	lg(LOG_ERR, "execl: %s: %s", sendmail, strerror(errno));
 	exit(1);
 }