use reverse DNS for EHLO/HELO

darcs-hash:20080301060142-5007d-7e9ef457cfd8fda6222bd32f96b2eb2b1929229f.gz

diff --git a/src/org/ibex/mail/SMTP.java b/src/org/ibex/mail/SMTP.java
index cf86164..df480ac 100644 (file)
--- a/src/org/ibex/mail/SMTP.java
+++ b/src/org/ibex/mail/SMTP.java
@@ -199,7 +199,8 @@ public class SMTP {
                     command = command.substring(10).trim();
                     from = command.equals("<>") ? null : new Address(command);
                     conn.println("250 " + from + " is syntactically correct");
-                    // FEATURE: perform SMTP validation on the address, reject if invalid
+                    // Don't perform SAV; discouraged here
+                    //   http://blog.fastmail.fm/2007/12/05/sending-email-servers-best-practice/
                 } else if (c.startsWith("RCPT TO:")) {
                     // some clients are broken and put RCPT first; we will tolerate this
                     command = command.substring(8).trim();
@@ -371,14 +372,23 @@ public class SMTP {
             Connection conn = null;
             try {
                 conn = new Connection(new Socket(mx, 25), InetAddress.getLocalHost().getHostName());
+                InetAddress localAddress = conn.getSocket().getLocalAddress();
+                String reverse = DNSUtil.reverseLookup(localAddress);
+                Log.info(SMTP.Outgoing.class,
+                         "outbound connection to " + mx + " uses " + localAddress + " [reverse: " + reverse + "]");
+                InetAddress relookup = InetAddress.getByName(reverse);
+                if (!relookup.equals(localAddress))
+                    Log.error(SMTP.Outgoing.class,
+                              "Warning: local machine fails forward-confirmed-reverse; " +
+                              reverse + " resolves to " + localAddress);
                 conn.setNewline("\r\n");
                 conn.setTimeout(60 * 1000);
                 check(conn.readln(), conn);  // banner
                 try {
-                    conn.println("EHLO " + conn.vhost);
+                    conn.println("EHLO " + reverse);
                     check(conn.readln(), conn);
                 } catch (SMTPException smtpe) {
-                    conn.println("HELO " + conn.vhost);
+                    conn.println("HELO " + reverse);
                     check(conn.readln(), conn);
                 }
                 String envelopeFrom = m.envelopeFrom==null ? "" : m.envelopeFrom.toString();