1 // 查找mx记录
 2             Record[] mxRecords = new Lookup(host, Type.MX).run();
 3             if(ArrayUtils.isEmpty(mxRecords)) return false;
 4             // 邮件服务器地址
 5             String mxHost = ((MXRecord)mxRecords[0]).getTarget().toString();
 6             if(mxRecords.length > 1) { // 优先级排序
 7                 List<Record> arrRecords = new ArrayList<Record>();
 8                 Collections.addAll(arrRecords, mxRecords);
 9                 Collections.sort(arrRecords, new Comparator<Record>() {
10
11                     public int compare(Record o1, Record o2) {
12                         return new CompareToBuilder().append(((MXRecord)o1).getPriority(), ((MXRecord)o2).getPriority()).toComparison();
13                     }
14
15                 });
16                 mxHost = ((MXRecord)arrRecords.get(0)).getTarget().toString();
17             }

mx

  1 import java.io.BufferedInputStream;
  2 import java.io.BufferedReader;
  3 import java.io.BufferedWriter;
  4 import java.io.IOException;
  5 import java.io.InputStreamReader;
  6 import java.io.OutputStreamWriter;
  7 import java.net.InetSocketAddress;
  8 import java.net.Socket;
  9 import java.util.ArrayList;
 10 import java.util.Collections;
 11 import java.util.Comparator;
 12 import java.util.List;
 13
 14 import org.apache.commons.lang.ArrayUtils;
 15 import org.apache.commons.lang.StringUtils;
 16 import org.apache.commons.lang.builder.CompareToBuilder;
 17 import org.xbill.DNS.Lookup;
 18 import org.xbill.DNS.MXRecord;
 19 import org.xbill.DNS.Record;
 20 import org.xbill.DNS.TextParseException;
 21 import org.xbill.DNS.Type;
 22
 23
 24 public class MailValid {
 25
 26     public static void main(String[] args) {
 27         System.out.println(new MailValid().valid("100582783@qq.com", "jootmir.org"));
 28     }
 29
 30     /**
 31      * 验证邮箱是否存在
 32      * <br>
 33      * 由于要读取IO，会造成线程阻塞
 34      *
 35      * @param toMail
 36      *         要验证的邮箱
 37      * @param domain
 38      *         发出验证请求的域名(是当前站点的域名，可以任意指定)
 39      * @return
 40      *         邮箱是否可达
 41      */
 42     public boolean valid(String toMail, String domain) {
 43         if(StringUtils.isBlank(toMail) || StringUtils.isBlank(domain)) return false;
 44         if(!StringUtils.contains(toMail, '@')) return false;
 45         String host = toMail.substring(toMail.indexOf('@') + 1);
 46         if(host.equals(domain)) return false;
 47         Socket socket = new Socket();
 48         try {
 49             // 查找mx记录
 50             Record[] mxRecords = new Lookup(host, Type.MX).run();
 51             if(ArrayUtils.isEmpty(mxRecords)) return false;
 52             // 邮件服务器地址
 53             String mxHost = ((MXRecord)mxRecords[0]).getTarget().toString();
 54             if(mxRecords.length > 1) { // 优先级排序
 55                 List<Record> arrRecords = new ArrayList<Record>();
 56                 Collections.addAll(arrRecords, mxRecords);
 57                 Collections.sort(arrRecords, new Comparator<Record>() {
 58
 59                     public int compare(Record o1, Record o2) {
 60                         return new CompareToBuilder().append(((MXRecord)o1).getPriority(), ((MXRecord)o2).getPriority()).toComparison();
 61                     }
 62
 63                 });
 64                 mxHost = ((MXRecord)arrRecords.get(0)).getTarget().toString();
 65             }
 66             // 开始smtp
 67             socket.connect(new InetSocketAddress(mxHost, 25));
 68             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new BufferedInputStream(socket.getInputStream())));
 69             BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
 70             // 超时时间(毫秒)
 71             long timeout = 6000;
 72             // 睡眠时间片段(50毫秒)
 73             int sleepSect = 50;
 74
 75             // 连接(服务器是否就绪)
 76             if(getResponseCode(timeout, sleepSect, bufferedReader) != 220) {
 77                 return false;
 78             }
 79
 80             // 握手
 81             bufferedWriter.write("HELO " + domain + "\r\n");
 82             bufferedWriter.flush();
 83             if(getResponseCode(timeout, sleepSect, bufferedReader) != 250) {
 84                 return false;
 85             }
 86             // 身份
 87             bufferedWriter.write("MAIL FROM: <check@" + domain + ">\r\n");
 88             bufferedWriter.flush();
 89             if(getResponseCode(timeout, sleepSect, bufferedReader) != 250) {
 90                 return false;
 91             }
 92             // 验证
 93             bufferedWriter.write("RCPT TO: <" + toMail + ">\r\n");
 94             bufferedWriter.flush();
 95             if(getResponseCode(timeout, sleepSect, bufferedReader) != 250) {
 96                 return false;
 97             }
 98             // 断开
 99             bufferedWriter.write("QUIT\r\n");
100             bufferedWriter.flush();
101             return true;
102         } catch (NumberFormatException e) {
103         } catch (TextParseException e) {
104         } catch (IOException e) {
105         } catch (InterruptedException e) {
106         } finally {
107             try {
108                 socket.close();
109             } catch (IOException e) {
110             }
111         }
112         return false;
113     }
114
115     private int getResponseCode(long timeout, int sleepSect, BufferedReader bufferedReader) throws InterruptedException, NumberFormatException, IOException {
116         int code = 0;
117         for(long i = sleepSect; i < timeout; i += sleepSect) {
118             Thread.sleep(sleepSect);
119             if(bufferedReader.ready()) {
120                 String outline = bufferedReader.readLine();
121                 // FIXME 读完……
122                 while(bufferedReader.ready())
123                     /*System.out.println(*/bufferedReader.readLine()/*)*/;
124                 /*System.out.println(outline);*/
125                 code = Integer.parseInt(outline.substring(0, 3));
126                 break;
127             }
128         }
129         return code;
130     }
131 }