src/org/ibex/mail/SMTP.java

   1 // Copyright 2000-2005 the Contributors, as shown in the revision logs.
   2 // Licensed under the Apache Public Source License 2.0 ("the License").
   3 // You may not use this file except in compliance with the License.
   4
   5 package org.ibex.mail;
   6 import org.ibex.mail.target.*;
   7 import org.ibex.util.*;
   8 import org.ibex.net.*;
   9 import org.ibex.io.*;
  10 import java.net.*;
  11 import java.io.*;
  12 import java.util.*;
  13 import java.text.*;
  14 import javax.naming.*;
  15 import javax.naming.directory.*;
  16
  17 // FIXME: inbound throttling/ratelimiting
  18
  19 // "Address enumeration detection" -- notice when it looks like somebody
  20 // is trying a raft of addresses.
  21
  22 // RFC's implemented
  23 // RFC2554: SMTP Service Extension for Authentication
  24 //     - did not implement section 5, though
  25 // RFC4616: SASL PLAIN
  26
  27 // Note: we can't actually use status codes for feedback if we accept
  28 // multiple destination addresses...  a failure on one and success on
  29 // the other...
  30
  31 // FIXME: logging: current logging sucks
  32 // FIXME: loop prevention
  33 // FIXME: probably need some throttling on outbound mail
  34
  35 // FEATURE: public static boolean validate(Address a)
  36 // FEATURE: rate-limiting
  37
  38 // FEATURE: infer messageid, date, if not present (?)
  39 // FEATURE: exponential backoff on retry time?
  40 // FEATURE: RFC2822, section 4.5.1: special "postmaster" address
  41 // FEATURE: RFC2822, section 4.5.4.1: retry strategies
  42 // FEATURE: RFC2822, section 5, multiple MX records, preferences, ordering
  43 // FEATURE: RFC2822, end of 4.1.2: backslashes in headers
  44 public class SMTP {
  45
  46     public static final SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z");
  47     public static final int numOutgoingThreads = 5;
  48
  49     private static final SqliteMailbox allmail =
  50         (SqliteMailbox)FileBasedMailbox
  51         .getFileBasedMailbox("/afs/megacz.com/mail/user/megacz/allmail", false);
  52
  53     public static final int GRAYLIST_MINWAIT =  1000 * 60 * 60;           // one hour
  54     public static final int GRAYLIST_MAXWAIT =  1000 * 60 * 60 * 24 * 5;  // five days
  55
  56     public static final Graylist graylist;
  57     public static final Whitelist whitelist;
  58     static {
  59         try {
  60             graylist =  new Graylist(Mailbox.STORAGE_ROOT+"/db/graylist.sqlite");
  61             whitelist = new Whitelist(Mailbox.STORAGE_ROOT+"/db/whitelist.sqlite");
  62         } catch (Exception e) {
  63             throw new RuntimeException(e);
  64         }
  65     }
  66
  67     public static final int MAX_MESSAGE_SIZE =
  68         Integer.parseInt(System.getProperty("org.ibex.mail.smtp.maxMessageSize", "-1"));
  69
  70     private static final Mailbox spool =
  71         FileBasedMailbox.getFileBasedMailbox(Mailbox.STORAGE_ROOT,false).slash("spool",true).slash("smtp",true).getMailbox();
  72
  73     static {
  74         for(int i=0; i<numOutgoingThreads; i++)
  75             new Outgoing().start();
  76     }
  77
  78     public static void enqueue(Message m) throws IOException {
  79         if (!m.envelopeTo.isLocal()) Outgoing.enqueue(m);
  80         else {
  81             try {
  82                 allmail.accept(m);
  83             } catch (Exception e) {
  84                 // FIXME incredibly gross hack
  85                 if (e.toString().indexOf("attempt to insert two messages with identical messageid")==-1)
  86                     Log.error(SMTP.class, e);
  87             }
  88             Target.root.accept(m);
  89         }
  90     }
  91
  92     public static class SMTPException extends MailException {
  93         int code;
  94         String message;
  95         public SMTPException(String s) {
  96             try {
  97                 code = Integer.parseInt(s.substring(0, s.indexOf(' ')));
  98                 message = s.substring(s.indexOf(' ')+1);
  99             } catch (NumberFormatException nfe) {
 100                 code = -1;
 101                 message = s;
 102             }
 103         }
 104         public String toString() { return "SMTP " + code + ": " + message; }
 105         public String getMessage() { return toString(); }
 106     }
 107
 108     // Server //////////////////////////////////////////////////////////////////////////////
 109
 110     public static class Server {
 111         public void handleRequest(Connection conn) throws IOException {
 112             conn.setTimeout(5 * 60 * 1000);
 113             conn.setNewline("\r\n");
 114             conn.println("220 " + conn.vhost + " ESMTP " + this.getClass().getName());
 115             Address from = null;
 116             Vector to = new Vector();
 117             boolean ehlo = false;
 118             String remotehost = null;
 119             String authenticatedAs = null;
 120             int failedRcptCount = 0;
 121             for(String command = conn.readln(); ; command = conn.readln()) try {
 122                 if (command == null) return;
 123                 Log.warn("**"+conn.getRemoteAddress()+"**", command);
 124                 String c = command.toUpperCase();
 125                 if (c.startsWith("HELO"))        {
 126                     remotehost = c.substring(5).trim();
 127                     conn.println("250 HELO " + conn.vhost);
 128                     from = null; to = new Vector();
 129                 } else if (c.startsWith("EHLO")) {
 130                     remotehost = c.substring(5).trim();
 131                     conn.println("250-"+conn.vhost);
 132                     //conn.println("250-AUTH");
 133                     conn.println("250-AUTH PLAIN");
 134                     //conn.println("250-STARTTLS");
 135                     conn.println("250 HELP");
 136                     ehlo = true;
 137                     from = null; to = new Vector();
 138                 } else if (c.startsWith("RSET")) { conn.println("250 reset ok");           from = null; to = new Vector();
 139                 } else if (c.startsWith("HELP")) { conn.println("214 you are beyond help.  see a trained professional.");
 140                 } else if (c.startsWith("VRFY")) { conn.println("502 VRFY not supported");
 141                 } else if (c.startsWith("EXPN")) { conn.println("502 EXPN not supported");
 142                 } else if (c.startsWith("NOOP")) { conn.println("250 OK");
 143                 } else if (c.startsWith("QUIT")) { conn.println("221 " + conn.vhost + " closing connection"); return;
 144                 } else if (c.startsWith("STARTTLS")) {
 145                     conn.println("220 starting TLS...");
 146                     conn.flush();
 147                     conn = conn.negotiateSSL(true);
 148                     from = null; to = new Vector();
 149                 } else if (c.startsWith("AUTH")) {
 150                     if (authenticatedAs != null) {
 151                         conn.println("503 you are already authenticated; you must reconnect to reauth");
 152                     } else {
 153                         String mechanism = command.substring(4).trim();
 154                         String rest = "";
 155                         if (mechanism.indexOf(' ')!=-1) {
 156                             rest      = mechanism.substring(mechanism.indexOf(' ')+1).trim();
 157                             mechanism = mechanism.substring(0, mechanism.indexOf(' '));
 158                         }
 159                         if (mechanism.equals("PLAIN")) {
 160                             // 538 Encryption required for requested authentication mechanism?
 161                             byte[] bytes = Encode.fromBase64(rest);
 162                             String authenticateUser = null;
 163                             String authorizeUser = null;
 164                             String password = null;
 165                             int start = 0;
 166                             for(int i=0; i<=bytes.length; i++) {
 167                                 if (i<bytes.length && bytes[i]!=0) continue;
 168                                 String result = new String(bytes, start, i-start, "UTF-8");
 169                                 if (authenticateUser==null)   authenticateUser = result;
 170                                 else if (authorizeUser==null) authorizeUser = result;
 171                                 else if (password==null)      password = result;
 172                                 start = i+1;
 173                             }
 174                             // FIXME: be smarter here
 175                             if (Main.auth.login(authorizeUser, password)!=null)
 176                                 authenticatedAs = authenticateUser;
 177                             conn.println("235 Authentication successful");
 178                             /*
 179                         } else if (mechanism.equals("CRAM-MD5")) {
 180                             String challenge = ;
 181                             conn.println("334 "+challenge);
 182                             String resp = conn.readln();
 183                             if (resp.equals("*")) {
 184                                 conn.println("501 client requested AUTH cancellation");
 185                             }
 186                         } else if (mechanism.equals("ANONYMOUS")) {
 187                         } else if (mechanism.equals("EXTERNAL")) {
 188                         } else if (mechanism.equals("DIGEST-MD5")) {
 189                             */
 190                         } else {
 191                             conn.println("504 unrecognized authentication type");
 192                         }
 193                         // on success, reset to initial state; client will EHLO again
 194                         from = null; to = new Vector();
 195                     }
 196                 } else if (c.startsWith("MAIL FROM:")) {
 197                     command = command.substring(10).trim();
 198                     from = command.equals("<>") ? null : new Address(command);
 199                     conn.println("250 " + from + " is syntactically correct");
 200                     // FEATURE: perform SMTP validation on the address, reject if invalid
 201                 } else if (c.startsWith("RCPT TO:")) {
 202                     // some clients are broken and put RCPT first; we will tolerate this
 203                     command = command.substring(8).trim();
 204                     if(command.indexOf(' ') != -1) command = command.substring(0, command.indexOf(' '));
 205                     Address addr = new Address(command);
 206                     if (conn.getRemoteAddress().isLoopbackAddress() || (from!=null&&from.toString().indexOf("johnw")!=-1)) {
 207                         conn.println("250 you are connected locally, so I will let you send");
 208                         to.addElement(addr);
 209                         if (!whitelist.isWhitelisted(addr))
 210                             whitelist.addWhitelist(addr);
 211                     } else if (authenticatedAs!=null) {
 212                         conn.println("250 you are authenticated as "+authenticatedAs+", so I will let you send");
 213                         to.addElement(addr);
 214                         if (!whitelist.isWhitelisted(addr))
 215                             whitelist.addWhitelist(addr);
 216                     } else if (addr.isLocal()) {
 217                         if (to.size() > 3) {
 218                             conn.println("536 sorry, limit on 3 RCPT TO's per DATA");
 219                         } else {
 220                             // FEATURE: should check the address further and give 550 if undeliverable
 221                             conn.println("250 " + addr + " is on this machine; I will deliver it");
 222                             to.addElement(addr);
 223                         }
 224                     } else {
 225                         conn.println("535 sorry, " + addr + " is not on this machine, you are not connected from localhost, and I will not relay without SMTP AUTH");
 226                         Log.warn("","535 sorry, " + addr + " is not on this machine, you are not connected from localhost, and I will not relay without SMTP AUTH");
 227                         failedRcptCount++;
 228                         if (failedRcptCount > 3) {
 229                             conn.close();
 230                             return;
 231                         }
 232                     }
 233                     conn.flush();
 234                 } else if (c.startsWith("DATA")) {
 235                     //if (from == null) { conn.println("503 MAIL FROM command must precede DATA"); continue; }
 236                     if (to == null || to.size()==0) { conn.println("503 RCPT TO command must precede DATA"); continue; }
 237                     if (!graylist.isWhitelisted(conn.getRemoteAddress()) && !conn.getRemoteAddress().isLoopbackAddress() && authenticatedAs==null) {
 238                         long when = graylist.getGrayListTimestamp(conn.getRemoteAddress(), from+"", to+"");
 239                         if (when == 0 || System.currentTimeMillis() - when > GRAYLIST_MAXWAIT) {
 240                             graylist.setGrayListTimestamp(conn.getRemoteAddress(), from+"", to+"",  System.currentTimeMillis());
 241                             conn.println("451 you are graylisted; please try back in one hour to be whitelisted");
 242                             Log.warn(conn.getRemoteAddress().toString(), "451 you are graylisted; please try back in one hour to be whitelisted");
 243                             conn.flush();
 244                             continue;
 245                         } else if (System.currentTimeMillis() - when > GRAYLIST_MINWAIT) {
 246                             graylist.addWhitelist(conn.getRemoteAddress());
 247                             conn.println("354 (you have been whitelisted) Enter message, ending with \".\" on a line by itself");
 248                             Log.warn(conn.getRemoteAddress().toString(), "has been whitelisted");
 249                         } else {
 250                             conn.println("451 you are still graylisted (since "+new java.util.Date(when)+")");
 251                             conn.flush();
 252                             Log.warn(conn.getRemoteAddress().toString(), "451 you are still graylisted (since "+new java.util.Date(when)+")");
 253                             continue;
 254                         }
 255                     } else {
 256                         conn.println("354 Enter message, ending with \".\" on a line by itself");
 257                     }
 258                     conn.flush();
 259                     try {
 260                         // FIXME: deal with messages larger than memory here?
 261                         StringBuffer buf = new StringBuffer();
 262                         buf.append("Received: from " + conn.getRemoteHostname() + " (" + remotehost + ")\r\n");
 263                         buf.append("          by "+conn.vhost+" ("+SMTP.class.getName()+") with "+(ehlo?"ESMTP":"SMTP") + "\r\n");
 264                         buf.append("          for ");
 265                         // FIXME: this is leaking BCC addrs
 266                         // for(int i=0; i<to.size(); i++) buf.append(to.elementAt(i) + " ");
 267                         buf.append("; " + dateFormat.format(new Date()) + "\r\n");
 268
 269                         // FIXME: some sort of stream transformer here?
 270                         while(true) {
 271                             String s = conn.readln();
 272                             if (s == null) throw new RuntimeException("connection closed");
 273                             if (s.equals(".")) break;
 274                             if (s.startsWith(".")) s = s.substring(1);
 275                             buf.append(s + "\r\n");
 276                             if (MAX_MESSAGE_SIZE != -1 && buf.length() > MAX_MESSAGE_SIZE && (from+"").indexOf("paperless")==-1) {
 277                                 Log.error("**"+conn.getRemoteAddress()+"**",
 278                                           "sorry, this mail server only accepts messages of less than " +
 279                                           ByteSize.toString(MAX_MESSAGE_SIZE));
 280                                 throw new MailException.Malformed("sorry, this mail server only accepts messages of less than " +
 281                                                                   ByteSize.toString(MAX_MESSAGE_SIZE));
 282                             }
 283                         }
 284                         String message = buf.toString();
 285                         Message m = null;
 286                         for(int i=0; i<to.size(); i++)
 287                             enqueue(m = Message.newMessage(Fountain.Util.create(message)).withEnvelope(from, (Address)to.elementAt(i)));
 288                         if (m != null) Log.info(SMTP.class, "accepted message: " + m.summary());
 289                         conn.println("250 message accepted");
 290                         conn.flush();
 291                         from = null; to = new Vector();
 292                     } catch (MailException.Malformed mfe) {    conn.println("501 " + mfe.toString());
 293                     } catch (MailException.MailboxFull mbf) {  conn.println("452 " + mbf);
 294                     } catch (Script.Later.LaterException le) { conn.println("453 try again later");
 295                     } catch (Script.Reject.RejectException re) {
 296                         Log.warn(SMTP.class, "rejecting message due to: " + re.reason + "\n   " + re.m.summary());
 297                         conn.println("501 " + re.reason);
 298                     }
 299                 } else                    { conn.println("500 unrecognized command"); }
 300             } catch (Message.Malformed e) { conn.println("501 " + e.toString()); }
 301         }
 302     }
 303
 304
 305     // Outgoing Mail Thread //////////////////////////////////////////////////////////////////////////////
 306
 307     public static class Outgoing extends Thread {
 308
 309         private static final HashMap deadHosts = new HashMap();
 310         public static void enqueue(Message m) throws IOException {
 311             if (m == null) { Log.warn(Outgoing.class, "attempted to enqueue(null)"); return; }
 312             String traces = m.headers.get("Received");
 313             if (traces!=null) {
 314                 int lines = 0;
 315                 for(int i=0; i<traces.length(); i++)
 316                     if (traces.charAt(i)=='\n' || traces.charAt(i)=='\r')
 317                         lines++;
 318                 if (lines > 100) { // required by rfc
 319                     Log.warn(SMTP.Outgoing.class, "Message with " + lines + " trace hops; dropping\n" + m.summary());
 320                     return;
 321                 }
 322             }
 323             synchronized(Outgoing.class) {
 324                 spool.insert(m, Mailbox.Flag.defaultFlags);
 325                 Outgoing.class.notifyAll();
 326             }
 327         }
 328
 329         public static boolean attempt(Message m) throws IOException { return attempt(m, false); }
 330         public static boolean attempt(Message m, boolean noBounces) throws IOException {
 331             if (m.envelopeTo == null) {
 332                 Log.warn(SMTP.Outgoing.class, "aieeee, null envelopeTo: " + m.summary());
 333                 return false;
 334             }
 335             InetAddress[] mx = getMailExchangerIPs(m.envelopeTo.host);
 336             if (mx.length == 0) {
 337                 if (!noBounces) {
 338                     enqueue(m.bounce("could not resolve " + m.envelopeTo.host));
 339                     return true;
 340                 } else {
 341                     Log.warn(SMTP.Outgoing.class, "could not resolve " + m.envelopeTo.host);
 342                     return false;
 343                 }
 344             }
 345             if (new Date().getTime() - m.arrival.getTime() > 1000 * 60 * 60 * 24 * 5) {
 346                 if (!noBounces) {
 347                     enqueue(m.bounce("could not send for 5 days"));
 348                     return true;
 349                 } else {
 350                     Log.warn(SMTP.Outgoing.class, "could not send for 5 days: " + m.summary());
 351                     return false;
 352                 }
 353             }
 354             for(int i=0; i<mx.length; i++) {
 355                 //if (deadHosts.contains(mx[i])) continue;
 356                 if (attempt(m, mx[i])) return true;
 357             }
 358             return false;
 359         }
 360
 361         private static void check(String s, Connection conn) {
 362             if (s==null) return;
 363             while (s.length() > 3 && s.charAt(3) == '-') s = conn.readln();
 364             //if (s.startsWith("4")||s.startsWith("5")) throw new SMTPException(s);
 365             if (!s.startsWith("2")&&!s.startsWith("3")) throw new SMTPException(s);
 366         }
 367         private static boolean attempt(final Message m, final InetAddress mx) {
 368             boolean accepted = false;
 369             Connection conn = null;
 370             try {
 371                 conn = new Connection(new Socket(mx, 25), InetAddress.getLocalHost().getHostName());
 372                 conn.setNewline("\r\n");
 373                 conn.setTimeout(60 * 1000);
 374                 check(conn.readln(), conn);  // banner
 375                 try {
 376                     conn.println("EHLO " + conn.vhost);
 377                     check(conn.readln(), conn);
 378                 } catch (SMTPException smtpe) {
 379                     conn.println("HELO " + conn.vhost);
 380                     check(conn.readln(), conn);
 381                 }
 382                 String envelopeFrom = m.envelopeFrom==null ? "" : m.envelopeFrom.toString();
 383                 conn.println("MAIL FROM:<" + envelopeFrom +">");            check(conn.readln(), conn);
 384                 conn.println("RCPT TO:<"   + m.envelopeTo.toString()+">");  check(conn.readln(), conn);
 385                 conn.println("DATA");                                       check(conn.readln(), conn);
 386
 387                 Headers head = new Headers(m.headers,
 388                                            new String[] {
 389                                                "return-path", null,
 390                                                "bcc", null
 391                                            });
 392                 Stream stream = head.getStream();
 393                 for(String s = stream.readln(); s!=null; s=stream.readln()) {
 394                     if (s.startsWith(".")) conn.print(".");
 395                     conn.println(s);
 396                 }
 397                 conn.println("");
 398                 stream = m.getBody().getStream();
 399                 for(String s = stream.readln(); s!=null; s=stream.readln()) {
 400                     if (s.startsWith(".")) conn.print(".");
 401                     conn.println(s);
 402                 }
 403                 conn.println(".");
 404                 String resp = conn.readln();
 405                 if (resp == null)
 406                     throw new SMTPException("server " + mx + " closed connection without accepting message");
 407                 check(resp, conn);
 408                 Log.warn(SMTP.Outgoing.class, "success: " + mx + " accepted " + m.summary() + "\n["+resp+"]");
 409                 accepted = true;
 410                 conn.close();
 411             } catch (SMTPException e) {
 412                 if (accepted) return true;
 413                 Log.warn(SMTP.Outgoing.class, "    unable to send; error=" + e);
 414                 Log.warn(SMTP.Outgoing.class, "      message: " + m.summary());
 415                 Log.warn(SMTP.Outgoing.class, e);
 416                 /*
 417                   // FIXME: we should not be bouncing here!
 418                 if (e.code >= 500 && e.code <= 599) {
 419                     try {
 420                         attempt(m.bounce("unable to deliver: " + e), true);
 421                     } catch (Exception ex) {
 422                         Log.error(SMTP.Outgoing.class, "exception while trying to deliver bounce; giving up completely");
 423                         Log.error(SMTP.Outgoing.class, ex);
 424                     }
 425                     return true;
 426                 }
 427                 */
 428                 return false;
 429             } catch (Exception e) {
 430                 if (accepted) return true;
 431                 Log.warn(SMTP.Outgoing.class, "    unable to send; error=" + e);
 432                 Log.warn(SMTP.Outgoing.class, "      message: " + m.summary());
 433                 Log.warn(SMTP.Outgoing.class, e);
 434                 //if (conn != null) Log.warn(SMTP.Outgoing.class, conn.dumpLog());
 435                 return false;
 436             } finally {
 437                 if (conn != null) conn.close();
 438             }
 439             return accepted;
 440         }
 441
 442         private static HashSet<Outgoing> threads = new HashSet<Outgoing>();
 443         private static int serials = 1;
 444         private int serial = serials++;
 445         private Mailbox.Iterator it;
 446
 447         public Outgoing() {
 448             synchronized(Outgoing.class) {
 449                 threads.add(this);
 450             }
 451         }
 452
 453         public void wake() {
 454             int count = spool.count(Query.all());
 455             Log.info(SMTP.Outgoing.class, "outgoing thread #"+serial+" woke up; " + count + " messages to send");
 456             try {
 457                 while(true) {
 458                     boolean good = false;
 459                     synchronized(Outgoing.class) {
 460                         it = spool.iterator();
 461                         OUTER: for(; it.next(); ) {
 462                             for(Outgoing o : threads)
 463                                 if (o!=this && o.it != null && o.it.uid()==it.uid())
 464                                     continue OUTER;
 465                             good = true;
 466                             break;
 467                         }
 468                     }
 469                     if (!good) break;
 470                     try {
 471                         if (attempt(it.cur())) it.delete();
 472                     } catch (Exception e) {
 473                         Log.error(SMTP.Outgoing.class, e);
 474                     }
 475                     Log.info(this, "sleeping for 3s...");
 476                     Thread.sleep(3000);
 477                 }
 478             } catch (Exception e) {
 479                 //if (e instanceof InterruptedException) throw e;
 480                 Log.error(SMTP.Outgoing.class, e);
 481             }
 482             Log.info(SMTP.Outgoing.class, "outgoing thread #"+serial+" going back to sleep");
 483             it = null;
 484         }
 485
 486         public void run() {
 487             try {
 488                 while(true) {
 489                     Log.setThreadAnnotation("[outgoing #"+serial+"] ");
 490                     wake();
 491                     Thread.sleep(1000);
 492                     synchronized(Outgoing.class) {
 493                         Outgoing.class.wait(5 * 60 * 1000);
 494                     }
 495                 }
 496             } catch (InterruptedException e) { Log.warn(this, e); }
 497         }
 498     }
 499
 500     public static InetAddress[] getMailExchangerIPs(String hostName) {
 501         InetAddress[] ret;
 502         try {
 503             Hashtable env = new Hashtable();
 504             env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
 505             DirContext ictx = new InitialDirContext(env);
 506             Attributes attrs = ictx.getAttributes(hostName, new String[] { "MX" });
 507             Attribute attr = attrs.get("MX");
 508             if (attr == null) {
 509                 ret = new InetAddress[1];
 510                 try {
 511                     ret[0] = InetAddress.getByName(hostName);
 512                     if (ret[0].equals(IP.getIP(127,0,0,1)) || ret[0].isLoopbackAddress()) throw new UnknownHostException();
 513                     return ret;
 514                 } catch (UnknownHostException uhe) {
 515                     Log.warn(SMTP.class, "no MX hosts or A record for " + hostName);
 516                     return new InetAddress[0];
 517                 }
 518             } else {
 519                 ret = new InetAddress[attr.size()];
 520                 NamingEnumeration ne = attr.getAll();
 521                 for(int i=0; ne.hasMore();) {
 522                     String mx = (String)ne.next();
 523                     // FIXME we should be sorting here
 524                     mx = mx.substring(mx.indexOf(" ") + 1);
 525                     if (mx.charAt(mx.length() - 1) == '.') mx = mx.substring(0, mx.length() - 1);
 526                     InetAddress ia = InetAddress.getByName(mx);
 527                     if (ia.equals(IP.getIP(127,0,0,1)) || ia.isLoopbackAddress()) continue;
 528                     ret[i++] = ia;
 529                 }
 530             }
 531         } catch (Exception e) {
 532             Log.warn(SMTP.class, "couldn't find MX host for " + hostName + " due to");
 533             Log.warn(SMTP.class, e);
 534             return new InetAddress[0];
 535         }
 536         return ret;
 537     }
 538 }