code: private String getMessageId(String response) {
  		if (StringUtils.isNullOrEmptyTrimmed(response)) {
  			return null;
  		}
  
  		try {
  			MailGunSendResponse res = JsonUtils.fromJson(response, MailGunSendResponse.class);
  			return res != null ? res.id : null;
  		}
  		catch (IllegalArgumentException e) {
  			log.warn("Failed to parse MailGun send response: ", e);
  			return null;
  		}
  	}
docs: {  "id": "<20180611195133.1.10869F48B8AD29FF@yourdomain.com>",  "message": "Queued. Thank you."}