JavaMail配額是限定或固定的號碼或郵件的數量在電子郵件存儲。JavaMail API為每個郵件服務請求調用計數配額。電子郵件服務可以適用下列配額標準：

• 外發郵件（包括附件）的最大大小。

• 郵件信息，包括附件的最大大小。

• 消息的最大大小時，管理員是一個收件人

對於配額管理的JavaMail有以下類彆：

Class	描述
public class Quota	This class represents a set of quotas for a given quota root. Each quota root has a set of resources, represented by the Quota.Resource class. Each resource has a name (for example, "STORAGE"), a current usage, and a usage limit. This has only one method setResourceLimit(String name, long limit).
public static class Quota.Resource	Represents an individual resource in a quota root.
public interface QuotaAwareStore	An interface implemented by Stores that support quotas. The getQuota and setQuota methods support the quota model defined by the IMAP QUOTA extension.GmailSSLStore, GmailStore, IMAPSSLStore, IMAPStore are the known implementing classes of this interface.

讓我們來看看和例子在下麵的章節會檢查郵件存儲名稱，並限製其使用。

創建Java類

創建一個Java類文件QuotaExample，是其內容如下：

package com.yiibai;

import java.util.Properties;

import javax.mail.Quota;
import javax.mail.Session;
import javax.mail.Store;

import com.sun.mail.imap.IMAPStore;

public class QuotaExample 
{
   public static void main(String[] args) 
   {
      try 
      {
         Properties properties = new Properties();
         properties.put("mail.store.protocol", "imaps");
         properties.put("mail.imaps.port", "993");
         properties.put("mail.imaps.starttls.enable", "true");
         Session emailSession = Session.getDefaultInstance(properties);
         // emailSession.setDebug(true);

         // create the IMAP3 store object and connect with the pop server
         Store store = emailSession.getStore("imaps");

         //change the user and password accordingly
         store.connect("imap.gmail.com", "abc@gmail.com", "*****");
         IMAPStore imapStore = (IMAPStore) store;
         System.out.println("imapStore ---" + imapStore);

         //get quota
         Quota[] quotas = imapStore.getQuota("INBOX");
         //Iterate through the Quotas
         for (Quota quota : quotas) {
            System.out.println(String.format("quotaRoot:'%s'",
               quota.quotaRoot));
            //Iterate through the Quota Resource
            for (Quota.Resource resource : quota.resources) {
               System.out.println(String.format(
                  "name:'%s', limit:'%s', usage:'%s'", resource.name,
                  resource.limit, resource.usage));
            }
         }
      } catch (Exception e) 
      {
         e.printStackTrace();
      }
   }
}

這裡是連接通過IMAP（imap.gmail.com）服務器的Gmail服務，為IMAPStore實現QuotaAwareStore。一旦你獲得了存儲對象，獲取配額陣列和遍曆並打印相關信息。

編譯並運行

現在，我們的類是準備好了，讓我們編譯上麵的類。我已經保存了類QuotaExample.java到目錄 : /home/manisha/JavaMailAPIExercise. 我們需要javax.mail.jar 和 activation.jar在classpath中。執行下麵的命令從命令提示符編譯類（兩個jar被放置在/home/manisha/ 目錄下）：

javac -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: QuotaExample.java

現在，這個類被編譯，執行下麵的命令來運行：

java -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: QuotaExample

驗證輸出

您應該看到類似的消息在命令控製台上：

imapStore ---imaps://abc%40gmail.com@imap.gmail.com
quotaRoot:''
name:'STORAGE', limit:'15728640', usage:'513'