File fetchmail-6.3.8-smtp_errors.patch of Package fetchmail.21926

# Patches fetchmail's behaviour for SMTP servers which: 
# 1) insist on using TLS - we do not want messages which cannot
# be sent due to server negotiation problems lost - rather we
# keep them on the mailserver. As users should realize rather
# quickly that something went wrong, the overhead shouldn't
# be considered that important.
# 2) use the 501 error code to mark spam - in such a case
# the 'antispam' option should be used
Index: fetchmail-6.4.1/sink.c
===================================================================
--- fetchmail-6.4.1.orig/sink.c
+++ fetchmail-6.4.1/sink.c
@@ -536,6 +536,19 @@ static int handle_smtp_report(struct que
 	free(responses[0]);
 	return(PS_TRANSIENT);
 
+	case 501: /* Syntax error in parameters or arguments */
+	/*
+	 * Some SMTP servers use this error code to refuse spam, however
+	 * as we don't want to delete message if e.g. the address is (possibly 
+	 * by mistake) malformed, user has to use the 'antispam' option to
+	 * treat this as spam symptom
+	 */
+	free(responses[0]);
+	if (outlevel > O_SILENT)
+		report_complete(stdout, 
+				GT_(" SMTP 501 error - if the server uses this code to report spam, include '501' in the 'antispam' option .\n"));
+	return(PS_TRANSIENT);
+
     default:
 	/* bounce non-transient errors back to the sender */
 	if (smtperr >= 500 && smtperr <= 599)
@@ -601,7 +614,7 @@ static int handle_smtp_report_without_bo
     case 553: /* invalid sending domain */
 	return(PS_REFUSED);
 
-    default:
+	default:
 	/* bounce non-transient errors back to the sender */
 	if (smtperr >= 500 && smtperr <= 599)
 	    return(PS_SUCCESS);