This is a modification by Manvendra Bhangui (www.indimail.org) of Erwin Hoffmann's (fehcom.de)
tcpserver.c included in his ucspi-tcp6-0.98 to make it work with spf check versus IPv4-mapped IPv6 addresses.

#############

diff -ruN net-original/ucspi-tcp6-0.98/src/tcpserver.c net/ucspi-tcp6-0.98/src/tcpserver.c
--- net-original/ucspi-tcp6-0.98/src/tcpserver.c	2013-01-11 21:18:19.000000000 +0100
+++ net/ucspi-tcp6-0.98/src/tcpserver.c	2013-08-06 11:14:37.000000000 +0200
@@ -53,6 +53,7 @@
 char remoteportstr[FMT_ULONG];
 char remoteip[16];
 char remoteipstr[IP6_FMT];
+char remoteip6str[IP6_FMT];
 static stralloc remotehostsa;
 char *remotehost = 0;
 
@@ -142,11 +143,15 @@
   char *stripaddr;
   int j;
 
-  if (!forcev6 && ip6_isv4mapped(remoteip)) mappedv4 = 1;
+  if (!forcev6 && ip6_isv4mapped(remoteip))
+    mappedv4 = 1;
   if (mappedv4)
-    remoteipstr[ip4_fmt(remoteipstr,remoteip+12)] = 0;
+    remoteipstr[ip4_fmt(remoteipstr, remoteip + 12)] = 0;
   else
-    remoteipstr[ip6_compactaddr(remoteipstr,remoteip)] = 0;
+  if (noipv6 && !forcev6)
+    remoteipstr[ip4_fmt(remoteipstr, remoteip)] = 0;
+  else
+    remoteipstr[ip6_compactaddr(remoteipstr, remoteip)] = 0;
 
   if (verbosity >= 2) {
     strnum[fmt_ulong(strnum,getpid())] = 0;
@@ -208,11 +213,15 @@
 	  remotehost = remotehostsa.s;
 	}
       }
-  if (!noipv6)  
-    remoteipstr[ip6_compactaddr(remoteipstr,remoteip)] = 0;
   env("TCPREMOTEIP",remoteipstr);
   env("TCPREMOTEPORT",remoteportstr);
   env("TCPREMOTEHOST",remotehost);
+  if (!noipv6) {
+    remoteip6str[ip6_compactaddr(remoteip6str, remoteip)] = 0;
+    env("TCP6REMOTEIP", remoteip6str);
+    env("TCP6REMOTEPORT", remoteportstr);
+    env("TCP6REMOTEHOST", remotehost);
+  }
 
   if (flagremoteinfo) {
     if (remoteinfo6(&tcpremoteinfo,remoteip,remoteport,localip,localport,timeout,netif) == -1)