diff -ruN e-smith-email-5.4.0.old/root/usr/local/sbin/smtp-auth-proxy.pl e-smith-email-5.4.0/root/usr/local/sbin/smtp-auth-proxy.pl
--- e-smith-email-5.4.0.old/root/usr/local/sbin/smtp-auth-proxy.pl	2013-02-06 13:56:01.000000000 -0800
+++ e-smith-email-5.4.0/root/usr/local/sbin/smtp-auth-proxy.pl	2013-12-14 12:27:33.000000000 -0800
@@ -114,13 +114,29 @@
 
     if ($smtp->supports("AUTH"))
     {
-	foreach (split (/ /, $self->get_property('Blacklist')))
-	  {${*$smtp}{'net_smtp_esmtp'}->{"AUTH"} =~ s/$_//;}
-	
-	unless ($smtp->auth($name, $pass))
+        my $authenticated = 0;
+        my $blacklist =  $self->get_property('Blacklist') || "";;
+        foreach my $method (split (/ /, ${*$smtp}{'net_smtp_esmtp'}->{"AUTH"}))
+        {
+            # Skip $method if in the blacklist
+            next unless ($blacklist !~ /$method/);
+            # Only present one auth method at a time to NET::SMTP
+            {${*$smtp}{'net_smtp_esmtp'}->{"AUTH"} = $method;}
+
+            if ($smtp->auth($name, $pass))
+            {
+                $authenticated++;
+                last;
+            }
+            else
+            {
+                warn "SMTP authentication (with $method) with ISP server failed\n";
+            }
+        }
+        unless ($authenticated)
         {
             print "451 Could not auth to mail server\n";
-            warn "SMTP authentication with ISP server failed\n";
+            warn "all SMTP authentication methods failed\n";
             $smtp->quit;
             exit;
         }
@@ -133,19 +149,19 @@
 
     my $discard = <STDIN>; # Swallow EHLO
     while (my $msg = shift @ehlo) {
-	 my $sep = (@ehlo ? "-" : " ");
-	 print "250$sep$msg";
+    my $sep = (@ehlo ? "-" : " ");
+    print "250$sep$msg";
   }
 
     die "can't fork: $!" unless defined ($kidpid = fork());
     if ($kidpid)
     {
-	print $smtp $_ while <STDIN>;
+        print $smtp $_ while <STDIN>;
         kill ("TERM" => $kidpid);
     }
     else
     {
-	print while <$smtp>;
+        print while <$smtp>;
         kill ("TERM" => getppid());
     }
 }