* successful delivery has been accomplished after SMTP_GIVE_UP seconds, the
* message will be returned to its sender.
*/
-#define SMTP_RETRY_INTERVAL 900 /* 15 minutes */
+#define SMTP_RETRY_INTERVAL 300 /* 5 minutes */
#define SMTP_RETRY_MAX 43200 /* 12 hours */
#define SMTP_GIVE_UP 432000 /* 5 days */