Java mail SendFailedException: Invalid Addresses 原因和解決

問題：使用javaMail發送郵件時（羣發），出現異常，提示信息爲：

org.springframework.mail.MailSendException: Failed messages: javax.mail.SendFailedException: Invalid Addresses;
  nested exception is:
    com.sun.mail.smtp.SMTPAddressFailedException: 550 Mailbox not found or access denied
;
  nested exception is:
    com.sun.mail.smtp.SMTPAddressFailedException: 550 Mailbox not found or access denied

原因：羣發的地址中，有一個或多個是無效的地址。可是，錯誤提示並沒有列出這些錯誤的地址來，靠肉眼找出來很麻煩。

解決：捕捉到異常時，把無效的地址打印出來：

        try {
			sender.send(message);
			logger.debug("簡單郵件已經發送。");
		}catch (MailSendException me){
			detectInvalidAddress(me);
		}

	private void detectInvalidAddress(MailSendException me) {
		Exception[] messageExceptions = me.getMessageExceptions();
		if (messageExceptions.length > 0) {
			Exception messageException = messageExceptions[0];
			if (messageException instanceof SendFailedException) {
				SendFailedException sfe = (SendFailedException) messageException;
				Address[] invalidAddresses = sfe.getInvalidAddresses();
				if(invalidAddresses != null) {
					StringBuilder addressStr = new StringBuilder();
					for (Address address : invalidAddresses) {
						addressStr.append(address.toString()).append("; ");
					}

					logger.error("發送郵件時發生異常！可能有無效的郵箱：{}", addressStr);
					return;
				}
			}
		}

		logger.error("發送郵件時發生異常！", me);
	}