diff --git Makefile Makefile
index dda83ca..26f1f13 100644
--- Makefile
+++ Makefile
@@ -367,10 +367,13 @@ make-compile warn-auto.sh systype
 	chmod 755 compile
 
 condredirect: \
-load condredirect.o qmail.o strerr.a fd.a sig.a wait.a seek.a env.a \
-substdio.a error.a str.a fs.a auto_qmail.o
-	./load condredirect qmail.o strerr.a fd.a sig.a wait.a \
-	seek.a env.a substdio.a error.a str.a fs.a auto_qmail.o 
+load condredirect.o srs.o rcpthosts.o cdb.a control.o constmap.o case.a \
+	getln.a stralloc.a alloc.a open.a qmail.o strerr.a fd.a sig.a \
+	wait.a seek.a env.a substdio.a error.a str.a fs.a auto_qmail.o
+	./load condredirect srs.o rcpthosts.o cdb.a control.o constmap.o \
+	case.a getln.a stralloc.a alloc.a open.a qmail.o strerr.a fd.a sig.a \
+	wait.a seek.a env.a substdio.a error.a str.a fs.a auto_qmail.o \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
 
 condredirect.0: \
 condredirect.1
@@ -378,7 +381,7 @@ condredirect.1
 
 condredirect.o: \
 compile condredirect.c sig.h readwrite.h exit.h env.h error.h fork.h \
-wait.h seek.h qmail.h substdio.h strerr.h substdio.h fmt.h
+wait.h seek.h qmail.h substdio.h strerr.h substdio.h fmt.h stralloc.h srs.h
 	./compile condredirect.c
 
 config: \
@@ -633,10 +636,13 @@ forgeries.7
 	nroff -man forgeries.7 > forgeries.0
 
 forward: \
-load forward.o qmail.o strerr.a alloc.a fd.a wait.a sig.a env.a \
-substdio.a error.a str.a fs.a auto_qmail.o
-	./load forward qmail.o strerr.a alloc.a fd.a wait.a sig.a \
-	env.a substdio.a error.a str.a fs.a auto_qmail.o 
+load forward.o srs.o qmail.o strerr.a control.o rcpthosts.o constmap.o \
+	cdb.a case.a open.a stralloc.a alloc.a getln.a \
+	fd.a wait.a sig.a env.a substdio.a error.a str.a fs.a auto_qmail.o
+	./load forward srs.o qmail.o strerr.a control.o rcpthosts.o constmap.o \
+	cdb.a case.a open.a stralloc.a alloc.a getln.a \
+	fd.a wait.a sig.a env.a substdio.a error.a str.a fs.a auto_qmail.o \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
 
 forward.0: \
 forward.1
@@ -644,7 +650,7 @@ forward.1
 
 forward.o: \
 compile forward.c sig.h readwrite.h exit.h env.h qmail.h substdio.h \
-strerr.h substdio.h fmt.h
+strerr.h substdio.h fmt.h stralloc.h srs.h
 	./compile forward.c
 
 fs.a: \
@@ -852,7 +858,7 @@ dnsptr dnsip dnsmxip dnsfq hostname ipmeprint qreceipt qsmhook qbiff \
 forward preline condredirect bouncesaying except maildirmake \
 maildir2mbox maildirwatch qail elq pinq install instpackage instchown \
 instcheck home home+df proc proc+df binm1 binm1+df binm2 binm2+df \
-binm3 binm3+df update_tmprsadh
+binm3 binm3+df update_tmprsadh srsfilter
 
 load: \
 make-load warn-auto.sh systype
@@ -1184,15 +1190,16 @@ qmail-header.5
 	nroff -man qmail-header.5 > qmail-header.0
 
 qmail-inject: \
-load qmail-inject.o headerbody.o hfield.o newfield.o quote.o now.o \
+load qmail-inject.o rcpthosts.o cdb.a srs.o headerbody.o hfield.o newfield.o quote.o now.o \
 control.o date822fmt.o constmap.o qmail.o case.a fd.a wait.a open.a \
 getln.a sig.a getopt.a datetime.a token822.o env.a stralloc.a alloc.a \
 substdio.a error.a str.a fs.a auto_qmail.o
-	./load qmail-inject headerbody.o hfield.o newfield.o \
+	./load qmail-inject rcpthosts.o cdb.a srs.o headerbody.o hfield.o newfield.o \
 	quote.o now.o control.o date822fmt.o constmap.o qmail.o \
 	case.a fd.a wait.a open.a getln.a sig.a getopt.a datetime.a \
 	token822.o env.a stralloc.a alloc.a substdio.a error.a \
-	str.a fs.a auto_qmail.o 
+	str.a fs.a auto_qmail.o \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
 
 qmail-inject.0: \
 qmail-inject.8
@@ -1219,15 +1226,16 @@ qmail-limits.9 conf-qmail conf-break conf-spawn
 	> qmail-limits.7
 
 qmail-local: \
-load qmail-local.o qmail.o quote.o now.o gfrom.o myctime.o \
+load qmail-local.o constmap.o control.o rcpthosts.o srs.o cdb.a qmail.o quote.o now.o gfrom.o myctime.o \
 slurpclose.o case.a getln.a getopt.a sig.a open.a seek.a lock.a fd.a \
 wait.a env.a stralloc.a alloc.a strerr.a substdio.a error.a str.a \
 fs.a datetime.a auto_qmail.o auto_patrn.o socket.lib
-	./load qmail-local qmail.o quote.o now.o gfrom.o myctime.o \
+	./load qmail-local constmap.o control.o rcpthosts.o srs.o cdb.a qmail.o quote.o now.o gfrom.o myctime.o \
 	slurpclose.o case.a getln.a getopt.a sig.a open.a seek.a \
 	lock.a fd.a wait.a env.a stralloc.a alloc.a strerr.a \
 	substdio.a error.a str.a fs.a datetime.a auto_qmail.o \
-	auto_patrn.o  `cat socket.lib`
+	auto_patrn.o  `cat socket.lib` \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
 
 qmail-local.0: \
 qmail-local.8
@@ -1531,16 +1539,17 @@ tcpto.h
 	./compile qmail-rspawn.c
 
 qmail-send: \
-load qmail-send.o qsutil.o control.o constmap.o newfield.o prioq.o \
+load qmail-send.o rcpthosts.o cdb.a srs.o qsutil.o control.o constmap.o newfield.o prioq.o \
 trigger.o fmtqfn.o quote.o now.o readsubdir.o qmail.o date822fmt.o \
 datetime.a case.a ndelay.a getln.a wait.a seek.a fd.a sig.a open.a \
 lock.a stralloc.a alloc.a substdio.a error.a str.a fs.a auto_qmail.o \
 auto_split.o env.a
-	./load qmail-send qsutil.o control.o constmap.o newfield.o \
+	./load qmail-send rcpthosts.o cdb.a srs.o qsutil.o control.o constmap.o newfield.o \
 	prioq.o trigger.o fmtqfn.o quote.o now.o readsubdir.o \
 	qmail.o date822fmt.o datetime.a case.a ndelay.a getln.a \
 	wait.a seek.a fd.a sig.a open.a lock.a stralloc.a alloc.a \
-	substdio.a error.a str.a fs.a auto_qmail.o auto_split.o env.a
+	substdio.a error.a str.a fs.a auto_qmail.o auto_split.o env.a \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
 
 qmail-send.0: \
 qmail-send.8
@@ -1896,6 +1905,26 @@ compile splogger.c error.h substdio.h subfd.h substdio.h exit.h str.h \
 scan.h fmt.h
 	./compile splogger.c
 
+srs.o: \
+compile srs.c srs.h auto_qmail.h stralloc.h
+	./compile srs.c
+
+
+srsfilter: \
+load srsfilter.o srs.o qmail.o strerr.a control.o rcpthosts.o constmap.o \
+	cdb.a case.a open.a stralloc.a alloc.a getln.a fd.a wait.a sig.a \
+	env.a substdio.a error.a str.a fs.a auto_qmail.o
+	./load srsfilter srs.o qmail.o strerr.a control.o rcpthosts.o constmap.o \
+	cdb.a case.a open.a stralloc.a alloc.a getln.a fd.a wait.a sig.a \
+	env.a substdio.a error.a str.a fs.a auto_qmail.o \
+	-I/usr/local/include -L/usr/local/lib -lsrs2
+
+srsfilter.o: \
+compile srsfilter.c sig.h readwrite.h exit.h env.h qmail.h substdio.h strerr.h \
+substdio.h fmt.h stralloc.h srs.h
+	./compile srsfilter.c
+
+
 str.a: \
 makelib str_len.o str_diff.o str_diffn.o str_cpy.o str_chr.o \
 str_rchr.o str_start.o byte_chr.o byte_rchr.o byte_diff.o byte_copy.o \
diff --git TARGETS TARGETS
index 23e36e4..b7f9563 100644
--- TARGETS
+++ TARGETS
@@ -196,6 +196,10 @@ ssl_timeoutio.o
 timeoutconn.o
 tcpto.o
 dns.o
+srsfilter
+srsfilter.o
+srs
+srs.o
 ip.o
 ipalloc.o
 hassalen.h
diff --git condredirect.c condredirect.c
index 593d2f5..732b752 100644
--- condredirect.c
+++ condredirect.c
@@ -10,6 +10,8 @@
 #include "strerr.h"
 #include "substdio.h"
 #include "fmt.h"
+#include "stralloc.h"
+#include "srs.h"
 
 #define FATAL "condredirect: fatal: "
 
@@ -68,6 +70,16 @@ char **argv;
   dtline = env_get("DTLINE");
   if (!dtline) strerr_die2x(100,FATAL,"DTLINE not set");
  
+  if (str_len(sender)) {
+    switch(srsforward(sender)) {
+      case -3: strerr_die2x(100,FATAL,srs_error.s); break;
+      case -2: strerr_die2x(111,FATAL,"out of memory"); break;
+      case -1: strerr_die2x(111,FATAL,"unable to read controls"); break;
+      case 0: break; // nothing
+      case 1: sender = srs_result.s; break;
+    }
+  }
+ 
   if (qmail_open(&qqt) == -1)
     strerr_die2sys(111,FATAL,"unable to fork: ");
   qmail_puts(&qqt,dtline);
diff --git forward.c forward.c
index e7390aa..f8eb2c7 100644
--- forward.c
+++ forward.c
@@ -6,11 +6,11 @@
 #include "strerr.h"
 #include "substdio.h"
 #include "fmt.h"
+#include "stralloc.h"
+#include "srs.h"
 
 #define FATAL "forward: fatal: "
 
-void die_nomem() { strerr_die2x(111,FATAL,"out of memory"); }
-
 struct qmail qqt;
 
 int mywrite(fd,buf,len) int fd; char *buf; int len;
@@ -42,6 +42,16 @@ char **argv;
   dtline = env_get("DTLINE");
   if (!dtline)
     strerr_die2x(100,FATAL,"DTLINE not set");
+
+  if (str_len(sender)) {
+    switch(srsforward(sender)) {
+      case -3: strerr_die2x(100,FATAL,srs_error.s); break;
+      case -2: strerr_die2x(111,FATAL,"out of memory"); break;
+      case -1: strerr_die2x(111,FATAL,"unable to read controls"); break;
+      case 0: break; // nothing
+      case 1: sender = srs_result.s; break;
+    }
+  }
  
   if (qmail_open(&qqt) == -1)
     strerr_die2sys(111,FATAL,"unable to fork: ");
diff --git hier.c hier.c
index 4549074..2eae0b3 100644
--- hier.c
+++ hier.c
@@ -127,6 +127,7 @@ void hier()
   c(auto_qmail,"bin","qmail-qmqpd",auto_uido,auto_gidq,0755);
   c(auto_qmail,"bin","qmail-qmtpd",auto_uido,auto_gidq,0755);
   c(auto_qmail,"bin","qmail-smtpd",auto_uido,auto_gidq,0755);
+  c(auto_qmail,"bin","srsfilter",auto_uido,auto_gidq,0755);
   c(auto_qmail,"bin","sendmail",auto_uido,auto_gidq,0755);
   c(auto_qmail,"bin","tcp-env",auto_uido,auto_gidq,0755);
   c(auto_qmail,"bin","qreceipt",auto_uido,auto_gidq,0755);
diff --git qmail-inject.c qmail-inject.c
index 753c18a..c55953a 100644
--- qmail-inject.c
+++ qmail-inject.c
@@ -22,6 +22,7 @@
 #include "auto_qmail.h"
 #include "newfield.h"
 #include "constmap.h"
+#include "srs.h"
 
 #define LINELEN 80
 
@@ -61,6 +62,11 @@ void perm() { _exit(100); }
 void temp() { _exit(111); }
 void die_nomem() {
  substdio_putsflush(subfderr,"qmail-inject: fatal: out of memory\n"); temp(); }
+void die_srs() {
+ substdio_puts("qmail-inject: fatal: ");
+ substdio_puts(subfderr,srs_error.s);
+ substdio_putsflush(subfderr,"\n");
+ perm(); }
 void die_invalid(sa) stralloc *sa; {
  substdio_putsflush(subfderr,"qmail-inject: fatal: invalid header field: ");
  substdio_putflush(subfderr,sa->s,sa->len); perm(); }
@@ -99,6 +105,17 @@ void exitnicely()
    int i;
 
    if (!stralloc_0(&sender)) die_nomem();
+   
+   if (!env_get("QMAILINJECT_SKIP_SRS") && (env_get("QMAILINJECT_FORCE_SRS") || (env_get("EXT") && env_get("HOST")))) {
+     switch(srsforward(sender.s)) {
+       case -3: die_srs(); break;
+       case -2: die_nomem(); break;
+       case -1: die_read(); break;
+       case 0: break;
+       case 1: if (!stralloc_copy(&sender,&srs_result)) die_nomem(); break;
+     }
+   }
+   
    qmail_from(&qqt,sender.s);
 
    for (i = 0;i < reciplist.len;++i)
diff --git qmail-local.c qmail-local.c
index 6fec288..3ed6713 100644
--- qmail-local.c
+++ qmail-local.c
@@ -28,6 +28,7 @@
 #include "myctime.h"
 #include "gfrom.h"
 #include "auto_patrn.h"
+#include "srs.h"
 
 void usage() { strerr_die1x(100,"qmail-local: usage: qmail-local [ -nN ] user homedir local dash ext domain sender aliasempty"); }
 
@@ -67,6 +68,14 @@ stralloc foo = {0};
 char buf[1024];
 char outbuf[1024];
 
+void die_control() { strerr_die1x(111,"Unable to read controls (#4.3.0)"); }
+void die_srs() {
+  if (!stralloc_copys(&foo,srs_error.s)) temp_nomem();
+  if (!stralloc_cats(&foo," (#4.3.0)")) temp_nomem();
+  if (!stralloc_0(&foo)) temp_nomem();
+  strerr_die1x(111,foo.s);
+}
+
 /* child process */
 
 char fntmptph[80 + FMT_ULONG * 2];
@@ -282,6 +291,15 @@ char **recips;
    qmail_put(&qqt,messline.s,messline.len);
   }
  while (match);
+ 
+ switch(srsforward(ueo.s)) {
+   case -3: die_srs(); break;
+   case -2: temp_nomem(); break;
+   case -1: die_control(); break;
+   case 0: break;
+   case 1: if (!stralloc_copy(&ueo,&srs_result)) temp_nomem(); break;
+ } 
+ 
  qmail_from(&qqt,ueo.s);
  while (*recips) qmail_to(&qqt,*recips++);
  qqx = qmail_close(&qqt);
diff --git qmail-send.c qmail-send.c
index c31b522..32d3afd 100644
--- qmail-send.c
+++ qmail-send.c
@@ -31,6 +31,7 @@
 #include "constmap.h"
 #include "fmtqfn.h"
 #include "readsubdir.h"
+#include "srs.h"
 
 /* critical timing feature #1: if not triggered, do not busy-loop */
 /* critical timing feature #2: if triggered, respond within fixed time */
@@ -55,6 +56,7 @@ stralloc bouncefrom = {0};
 stralloc bouncehost = {0};
 stralloc doublebounceto = {0};
 stralloc doublebouncehost = {0};
+stralloc srs_domain = {0};
 
 char strnum2[FMT_ULONG];
 char strnum3[FMT_ULONG];
@@ -689,9 +691,31 @@ unsigned long id;
     { log1("warning: unable to start qmail-queue, will try later\n"); return 0; }
    qp = qmail_qp(&qqt);
 
-   if (*sender.s) { bouncesender = ""; bouncerecip = sender.s; }
-   else { bouncesender = "#@[]"; bouncerecip = doublebounceto.s; }
-
+   if (*sender.s) {
+     if (srs_domain.len) {
+       int j = 0;
+       j = byte_rchr(sender.s, sender.len, '@');
+       if (j < sender.len) {
+         if (srs_domain.len == sender.len - j - 1 && stralloc_starts(&srs_domain, sender.s + j + 1)) {
+           switch(srsreverse(sender.s)) {
+             case -3: log1(srs_error.s); log1("\n"); _exit(111); break;
+             case -2: nomem(); break;
+             case -1: log1("alert: unable to read controls\n"); _exit(111); break;
+             case 0: break;
+             case 1: if (!stralloc_copy(&sender,&srs_result)) nomem(); break;
+           }
+           if (chdir(auto_qmail) == -1) { log1("alert: unable to switch to home directory\n"); _exit(111); }
+           if (chdir("queue") == -1) { log1("alert: unable to switch to queue directory\n"); _exit(111); }
+         }
+       }
+     }
+     bouncesender = "";
+     bouncerecip = sender.s;
+   } else {
+     bouncesender = "#@[]";
+     bouncerecip = doublebounceto.s;
+   }
+   
    while (!newfield_datemake(now())) nomem();
    qmail_put(&qqt,newfield_date.s,newfield_date.len);
    qmail_puts(&qqt,"From: ");
@@ -1449,6 +1473,8 @@ int getcontrols() { if (control_init() == -1) return 0;
  if (control_rldef(&bouncefrom,"control/bouncefrom",0,"MAILER-DAEMON") != 1) return 0;
  if (control_rldef(&bouncehost,"control/bouncehost",1,"bouncehost") != 1) return 0;
  if (control_rldef(&doublebouncehost,"control/doublebouncehost",1,"doublebouncehost") != 1) return 0;
+ if (control_readline(&srs_domain,"control/srs_domain") == -1) return 0;
+ if (srs_domain.len && !stralloc_0(&srs_domain)) return 0;
  if (control_rldef(&doublebounceto,"control/doublebounceto",0,"postmaster") != 1) return 0;
  if (!stralloc_cats(&doublebounceto,"@")) return 0;
  if (!stralloc_cat(&doublebounceto,&doublebouncehost)) return 0;
diff --git qmail-showctl.c qmail-showctl.c
index 813c640..b67fdff 100644
--- qmail-showctl.c
+++ qmail-showctl.c
@@ -283,6 +283,11 @@ void main()
 
   do_str("smtpgreeting",1,"smtpgreeting","SMTP greeting: 220 ");
   do_lst("smtproutes","No artificial SMTP routes.","SMTP route: ","");
+  do_str("srs_domain",0,"","SRS domain name is ");
+  do_lst("srs_secrets","No secrets","","");
+  do_int("srs_maxage","21","SRS maxage is ","");
+  do_int("srs_hashlength","4","SRS hashlength is ","");
+  do_int("srs_hashmin","4","SRS hashmin is ","");
   do_int("timeoutconnect","60","SMTP client connection timeout is "," seconds");
   do_int("timeoutremote","1200","SMTP client data timeout is "," seconds");
   do_int("timeoutsmtpd","1200","SMTP server data timeout is "," seconds");
@@ -318,6 +323,11 @@ void main()
     if (str_equal(d->d_name,"rcpthosts")) continue;
     if (str_equal(d->d_name,"smtpgreeting")) continue;
     if (str_equal(d->d_name,"smtproutes")) continue;
+    if (str_equal(d->d_name,"srs_domain")) continue;
+    if (str_equal(d->d_name,"srs_secrets")) continue;
+    if (str_equal(d->d_name,"srs_maxage")) continue;
+    if (str_equal(d->d_name,"srs_hashlength")) continue;
+    if (str_equal(d->d_name,"srs_hashmin")) continue;
     if (str_equal(d->d_name,"timeoutconnect")) continue;
     if (str_equal(d->d_name,"timeoutremote")) continue;
     if (str_equal(d->d_name,"timeoutsmtpd")) continue;
diff --git srs.c srs.c
new file mode 100644
index 0000000..ce09ab0
--- /dev/null
+++ srs.c
@@ -0,0 +1,166 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include </usr/local/include/srs2.h>
+#include "auto_qmail.h"
+#include "stralloc.h"
+#include "srs.h"
+
+static stralloc srs_domain = {0};
+static stralloc srs_secrets = {0};
+static unsigned int srs_maxage = 0;
+static unsigned int srs_hashlength = 0;
+static unsigned int srs_hashmin = 0;
+static unsigned int srs_alwaysrewrite = 0;
+static stralloc srs_separator = {0};
+
+stralloc srs_result = {0};
+stralloc srs_error = {0};
+
+static int setup_ok = 0;
+static int srs_secrets_ok = 0;
+
+static int setup(int with_rcpthosts) {
+
+  if (setup_ok == 1) return 1;
+
+  if (chdir(auto_qmail) == -1) return -1;
+  if (control_init() == -1) return -1;
+
+  if (control_readline(&srs_domain,"control/srs_domain") == -1) return -1;
+  if (srs_domain.len) {
+    if (!stralloc_0(&srs_domain)) return -2;
+  } else {
+    return 0;
+  }
+
+  srs_secrets_ok = control_readfile(&srs_secrets,"control/srs_secrets",0);
+  if (srs_secrets_ok == -1) return -1;
+  
+  if (control_readint(&srs_maxage,"control/srs_maxage") == -1) return 0;
+  if (control_readint(&srs_hashlength,"control/srs_hashlength") == -1) return 0;
+  if (control_readint(&srs_hashmin,"control/srs_hashmin") == -1) return 0;
+  if (srs_hashmin > srs_hashlength) srs_hashmin = srs_hashlength;
+  
+  if (control_readint(&srs_alwaysrewrite,"control/srs_alwaysrewrite") == -1) return 0;
+  
+  if (control_readline(&srs_separator,"control/srs_separator") == -1) return -1;
+  if (srs_separator.len && !stralloc_0(&srs_separator)) return -2;
+  if (srs_separator.len && srs_separator.s[0] != '-' && srs_separator.s[0] != '+' && srs_separator.s[0] != '=') {
+    if (!stralloc_copys(&srs_separator,"")) return -2;
+  }
+  
+  if (!srs_alwaysrewrite) {
+    if (with_rcpthosts && rcpthosts_init() == -1) return -1;
+  }
+
+  setup_ok = 1;
+  return 1;
+  
+}
+
+static int srs_error_str(int code) {
+  if (!stralloc_copys(&srs_error,"SRS: ")) return -2;
+  if (!stralloc_cats(&srs_error,srs_strerror(code))) return -2;
+  if (!stralloc_0(&srs_error)) return -2;   
+  return -3;
+}
+
+
+int srsforward(char *address) {
+  int x = 0;
+
+  /* Return if setup was unsucessfull */
+  x = setup(1);
+  if (x < 1) return(x);
+  
+  /* Return zero if null-sender */
+  x = str_len(address);
+  if (x <= 1) return 0;
+
+  /* Return zero if local address */
+  if (!srs_alwaysrewrite && rcpthosts(address,x) == 1) return 0;  
+  
+  /* Now it's time to rewrite the envelope */
+  char srsaddress[1000];
+
+  srs_t *srs; 
+  srs = srs_new();
+  if (srs_maxage > 0) srs->maxage = srs_maxage;
+  if (srs_hashlength > 0) srs->hashlength = srs_hashlength;
+  if (srs_hashmin > 0) srs->hashmin = srs_hashmin;
+  
+  if (srs_alwaysrewrite){  
+    x = srs_set_alwaysrewrite(srs, TRUE);
+    if (x != SRS_SUCCESS) return srs_error_str(x);
+  }
+  
+  if (srs_separator.len) {
+    x = srs_set_separator(srs, srs_separator.s[0]); 
+    if (x != SRS_SUCCESS) return srs_error_str(x);
+  }
+  
+  int i = 0;
+  int j = 0;
+  for (j = 0;j < srs_secrets.len;++j)
+    if (!srs_secrets.s[j]) {
+      x = srs_add_secret(srs, srs_secrets.s + i);
+      if (x != SRS_SUCCESS) return srs_error_str(x);
+      i = j + 1;
+    }
+  
+  x = srs_forward(srs, srsaddress, 1000, address, srs_domain.s);
+  if (x != SRS_SUCCESS) return srs_error_str(x);
+  
+  if (!stralloc_copys(&srs_result,srsaddress)) return -2;
+  if (!stralloc_0(&srs_result)) return -2;
+  
+  srs_free(srs);
+  
+  return 1;
+}
+
+int srsreverse(char *srsaddress) {
+  int x = 0;
+
+  /* Return if setup was unsucessfull */
+  x = setup(0);
+  if (x < 1) return(x);
+  
+  /* Return error if null-sender */
+  x = str_len(srsaddress);
+  if (x <= 1) return -3;
+  
+  /* Now it's time to rewrite the envelope */
+  char address[1000];
+
+  srs_t *srs;
+  srs = srs_new();
+  if (srs_maxage > 0) srs->maxage = srs_maxage;
+  if (srs_hashlength > 0) srs->hashlength = srs_hashlength;
+  if (srs_hashmin > 0) srs->hashmin = srs_hashmin;
+  
+  if (srs_separator.len) {
+    x = srs_set_separator(srs, srs_separator.s[0]); 
+    if (x != SRS_SUCCESS) return srs_error_str(x);
+  }
+
+  int i = 0;
+  int j = 0;
+  for (j = 0;j < srs_secrets.len;++j)
+    if (!srs_secrets.s[j]) {
+      x = srs_add_secret(srs, srs_secrets.s + i);
+      if (x != SRS_SUCCESS) return srs_error_str(x);
+      i = j + 1;
+    }
+    
+  x = srs_reverse(srs, address, 1000, srsaddress);
+  if (x != SRS_SUCCESS) return srs_error_str(x);
+  
+  if (!stralloc_copys(&srs_result,address)) return -2;
+  if (!stralloc_0(&srs_result)) return -2;
+  
+  srs_free(srs);
+  
+  return 1;
+}
+
diff --git srs.h srs.h
new file mode 100644
index 0000000..79067e4
--- /dev/null
+++ srs.h
@@ -0,0 +1,9 @@
+#ifndef SRS_H
+#define SRS_H
+
+extern stralloc srs_result;
+extern stralloc srs_error;
+extern int srsforward(char *);
+extern int srsreverse(char *);
+
+#endif
diff --git srsfilter.c srsfilter.c
new file mode 100644
index 0000000..3ed5544
--- /dev/null
+++ srsfilter.c
@@ -0,0 +1,137 @@
+#include "sig.h"
+#include "readwrite.h"
+#include "exit.h"
+#include "env.h"
+#include "qmail.h"
+#include "strerr.h"
+#include "substdio.h"
+#include "fmt.h"
+#include "stralloc.h"
+#include "srs.h"
+
+#define FATAL "srsfilter: fatal: "
+#define IGNORE "srsfilter: ignore: "
+
+void die_nomem() { strerr_die2x(111,FATAL,"out of memory"); }
+
+struct qmail qqt;
+
+stralloc line = {0};
+int flagbody = 0;
+int flagnewline = 0;
+int flagto = 0;
+int seento = 0;
+
+void newheader() {
+  if (!stralloc_copyb(&line,"To: ",4)) die_nomem();
+  if (!stralloc_cat(&line,&srs_result)) die_nomem();
+  ++flagto; ++seento;
+}
+
+void skipheader() {
+  if (!stralloc_copys(&line,"")) die_nomem();
+}
+
+void printheader() {
+  qmail_put(&qqt, line.s, line.len);
+  qmail_put(&qqt,"\n",1);
+  if (!stralloc_copys(&line,"")) die_nomem();
+}
+
+int mywrite(fd,buf,len) int fd; char *buf; int len;
+{
+  int i;
+  if (flagbody) {
+    qmail_put(&qqt,buf,len);
+    return len;
+  } else {
+    i = 0;
+    while (buf[i]) {
+      if (buf[i] == '\n') {
+        if (flagnewline) {
+          if (!seento) { newheader(); printheader(); }
+          qmail_put(&qqt,"\n",1); i++; flagbody = 1; continue;
+        }
+        if (flagto && (line.s[0] == ' ' || line.s[0] == '\t')) {
+          skipheader(); i++; continue;
+        }
+        if (line.len > 2 && line.s[2] == ':' && (line.s[1] == 'o' ||
+        line.s[1] == 'O') && (line.s[0] == 'T' || line.s[0] == 't')) {
+          if (seento) { skipheader(); i++; continue; }
+          newheader();
+        } else { flagto = 0; }
+        printheader();
+        flagnewline = 1;
+      } else {
+        if (!stralloc_append(&line,&buf[i])) die_nomem();
+        flagnewline = 0;
+      }
+      ++i;
+    }
+    return len;
+  }
+}
+
+char inbuf[SUBSTDIO_INSIZE];
+char outbuf[1];
+substdio ssin = SUBSTDIO_FDBUF(read,0,inbuf,sizeof inbuf);
+substdio ssout = SUBSTDIO_FDBUF(mywrite,-1,outbuf,sizeof outbuf);
+
+char num[FMT_ULONG];
+
+void main(argc,argv)
+int argc;
+char **argv;
+{
+  char *ext2;
+  char *host;
+  char *sender;
+  char *qqx;
+ 
+  sig_pipeignore();
+ 
+  sender = env_get("SENDER");
+  if (!sender)
+    strerr_die2x(100,FATAL,"SENDER not set");
+  if (str_len(sender)) {
+    /* Return zero, the message will not bounce back */
+    strerr_die2x(0,IGNORE,"SENDER must be empty");
+  }
+  ext2 = env_get("EXT2");
+  if (!ext2)
+    strerr_die2x(100,FATAL,"EXT2 not set");
+  host = env_get("HOST");
+  if (!host)
+    strerr_die2x(100,FATAL,"HOST not set");
+    
+  switch(srsreverse(ext2)) {
+    case -3: strerr_die2x(100,FATAL,srs_error.s); break;
+    case -2: die_nomem(); break;
+    case -1: strerr_die2x(111,FATAL,"unable to read controls"); break;
+    case 0: strerr_die2x(100,FATAL,"unable to rewrite envelope"); break;
+  }
+ 
+  if (qmail_open(&qqt) == -1)
+    strerr_die2x(111,FATAL,"unable to fork");
+  if (substdio_copy(&ssout,&ssin) != 0)
+    strerr_die2x(111,FATAL,"unable to read message");
+  substdio_flush(&ssout);
+  
+  if (!flagbody) {
+    qmail_fail(&qqt);
+    strerr_die2x(100,FATAL,"unable to read message body");
+  }
+
+  num[fmt_ulong(num,qmail_qp(&qqt))] = 0;
+
+  /* Always from nullsender */
+  qmail_from(&qqt,"");
+  
+  qmail_to(&qqt,srs_result.s);
+  
+  qqx = qmail_close(&qqt);
+  if (*qqx) strerr_die2x(*qqx == 'D' ? 100 : 111,FATAL,qqx + 1);
+  strerr_die2x(0,"srsfilter: qp ",num);
+
+}
+