diff --git a/server/email.go b/server/email.go
index 2a403dd6801a23d0d600b5504f1b5f20344725c5..73faabd58c149ba89bcce989a2beb1ac8dcfd709 100644
--- a/server/email.go
+++ b/server/email.go
@@ -60,7 +60,8 @@ 		return fmt.Errorf("internal system error")
 	}
 	rcpt, err := gomail.ParseAddress(to)
 	if err != nil {
-		panic(errors.New("Failed to parse sender address"))
+		log.Printf("Warning: mail::error-to is invalid: %v", err)
+		return fmt.Errorf("internal system error")
 	}
 	addr := mail.Address(*rcpt)
 	header.SetAddressList("To", []*mail.Address{&addr})