diff -ruN --exclude=CVS /usr/ports//mail/fetchmail/Makefile ./Makefile
--- /usr/ports//mail/fetchmail/Makefile	2012-02-25 00:56:18.000000000 +0100
+++ ./Makefile	2012-08-13 22:46:33.000000000 +0200
@@ -12,6 +12,7 @@
 
 PORTNAME=	fetchmail
 PORTVERSION=	6.3.21
+PORTREVISION=	1
 CATEGORIES=	mail ipv6
 MASTER_SITES=	BERLIOS/${PORTNAME}/ \
 		SF/${PORTNAME}/branch_6.3/ \
diff -ruN --exclude=CVS /usr/ports//mail/fetchmail/files/patch-3fbc7c ./files/patch-3fbc7c
--- /usr/ports//mail/fetchmail/files/patch-3fbc7c	1970-01-01 01:00:00.000000000 +0100
+++ ./files/patch-3fbc7c	2012-08-13 22:46:13.000000000 +0200
@@ -0,0 +1,38 @@
+commit 3fbc7cd331602c76f882d1b507cd05c1d824ba8b
+Author: Matthias Andree <matthias.andree@gmx.de>
+Date:   Mon Aug 13 20:48:12 2012 +0200
+
+    Fix crash: Handle invalid base64 in NTLM challenge.
+    
+    Some servers, for instance the MS Exchange servers deployed by the
+    US-American National Aeronautics and Space Administration (NASA),
+    aborted the NTLM protocol exchange after receiving the initial request.
+    
+    Fetchmail did not detect that there was an error message, rather than
+    NTLM protocol exchange, and caught a segmentation fault while reading
+    from a bad location.
+    
+    Detect base64 decoding errors, and return PS_AUTHFAIL in this case.
+    
+    Reported by J[ames] Porter Clark.
+
+diff --git a/ntlmsubr.c b/ntlmsubr.c
+index f9d2733..9321d26 100644
+--- a/ntlmsubr.c
++++ b/ntlmsubr.c
+@@ -55,7 +55,14 @@ int ntlm_helper(int sock, struct query *ctl, const char *proto)
+     if ((result = gen_recv(sock, msgbuf, sizeof msgbuf)))
+ 	goto cancelfail;
+ 
+-    (void)from64tobits (&challenge, msgbuf, sizeof(challenge));
++    if ((result = from64tobits (&challenge, msgbuf, sizeof(challenge))) < 0)
++    {
++	report (stderr, GT_("could not decode BASE64 challenge\n"));
++	/* We do not goto cancelfail; the server has already sent the
++	 * tagged reply, so the protocol exchange has ended, no need
++	 * for us to send the asterisk. */
++	return PS_AUTHFAIL;
++    }
+ 
+     if (outlevel >= O_DEBUG)
+ 	dumpSmbNtlmAuthChallenge(stdout, &challenge);