String MAIL_SMTP_CONNECTIONTIMEOUT ="mail.smtp.connectiontimeout";
String MAIL_SMTP_TIMEOUT = "mail.smtp.timeout";
String MAIL_SMTP_WRITETIMEOUT = "mail.smtp.writetimeout";
String MAIL_SOCKET_TIMEOUT = "60000";
 
// Set a fixed timeout of 60s for all operations -
// the default timeout is "infinite"
props.put(MAIL_SMTP_CONNECTIONTIMEOUT, MAIL_SOCKET_TIMEOUT);
props.put(MAIL_SMTP_TIMEOUT, MAIL_SOCKET_TIMEOUT);
props.put(MAIL_SMTP_WRITETIMEOUT, MAIL_SOCKET_TIMEOUT);

// Only cache DNS lookups for 10 seconds
java.security.Security.setProperty("networkaddress.cache.ttl","10");