diff --git a/README.md b/README.md
index fd85d40..f2f1ab0 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,4 @@
 # sendmail
 
+Implementation of the sendmail Mail Filter API
+
diff --git a/libmilter-site.config.m4 b/libmilter-site.config.m4
new file mode 100644
index 0000000..86c5313
--- /dev/null
+++ b/libmilter-site.config.m4
@@ -0,0 +1,15 @@
+dnl Enable libmilter with a pool of workers
+APPENDDEF(`conf_libmilter_ENVDEF',`-D_FFR_WORKERS_POOL=1')
+APPENDDEF(`conf_libmilter_ENVDEF',`-DMIN_WORKERS=4')
+dnl Use poll instead of select
+APPENDDEF(`conf_libmilter_ENVDEF',`-DSM_CONF_POLL=1')
+dnl Enable IPv6
+APPENDDEF(`conf_libmilter_ENVDEF',`-DNETINET6=1')
+dnl Add -fPIC
+APPENDDEF(`conf_libmilter_ENVDEF',`-fPIC')
+dnl Permissions
+APPENDDEF(`confINCGRP',`root')
+APPENDDEF(`confLIBGRP',`root')
+APPENDDEF(`confMBINGRP',`root')
+APPENDDEF(`confSBINGRP',`root')
+APPENDDEF(`confBINGRP',`root')
diff --git a/sendmail-8.17.1-fd-passing-libmilter.patch b/sendmail-8.17.1-fd-passing-libmilter.patch
new file mode 100644
index 0000000..01d35f5
--- /dev/null
+++ b/sendmail-8.17.1-fd-passing-libmilter.patch
@@ -0,0 +1,76 @@
+Description: systemd-like socket activation support for libmilter
+Author: Mikhail Gusarov <dottedmag@debian.org
+--- a/libmilter/docs/smfi_setconn.html
++++ b/libmilter/docs/smfi_setconn.html
+@@ -44,6 +44,7 @@ Set the socket through which this filter
+ 	<LI><CODE>{unix|local}:/path/to/file</CODE> -- A named pipe.
+ 	<LI><CODE>inet:port@{hostname|ip-address}</CODE> -- An IPV4 socket.
+ 	<LI><CODE>inet6:port@{hostname|ip-address}</CODE> -- An IPV6 socket.
++	<LI><CODE>fd:number</CODE> -- Pre-opened file descriptor.
+ 	</UL>
+ 	</TD></TR>
+     </TABLE>
+--- a/libmilter/listener.c
++++ b/libmilter/listener.c
+@@ -197,6 +197,11 @@
+ 			L_socksize = sizeof addr.sin6;
+ 		}
+ #endif /* NETINET6 */
++		else if (strcasecmp(p, "fd") == 0)
++		{
++			addr.sa.sa_family = AF_UNSPEC;
++			L_socksize = sizeof (_SOCK_ADDR);
++		}
+ 		else
+ 		{
+ 			smi_log(SMI_LOG_ERR, "%s: unknown socket type %s",
+@@ -443,7 +448,21 @@
+ 	}
+ #endif /* NETINET || NETINET6 */
+
+-	sock = socket(addr.sa.sa_family, SOCK_STREAM, 0);
++	if (addr.sa.sa_family == AF_UNSPEC)
++	{
++		char *end;
++		sock = strtol(colon, &end, 10);
++		if (*end != '\0' || sock < 0)
++		{
++			smi_log(SMI_LOG_ERR, "%s: expected positive integer as fd, got %s", name, colon);
++			return INVALID_SOCKET;
++		}
++	}
++	else
++	{
++		sock = socket(addr.sa.sa_family, SOCK_STREAM, 0);
++	}
++
+ 	if (!ValidSocket(sock))
+ 	{
+ 		smi_log(SMI_LOG_ERR,
+@@ -466,6 +485,7 @@
+ #if NETUNIX
+ 	    addr.sa.sa_family != AF_UNIX &&
+ #endif
++	    addr.sa.sa_family != AF_UNSPEC &&
+ 	    setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *) &sockopt,
+ 		       sizeof(sockopt)) == -1)
+ 	{
+@@ -511,7 +531,8 @@
+ 	}
+ #endif /* NETUNIX */
+
+-	if (bind(sock, &addr.sa, L_socksize) < 0)
++	if (addr.sa.sa_family != AF_UNSPEC &&
++	    bind(sock, &addr.sa, L_socksize) < 0)
+ 	{
+ 		smi_log(SMI_LOG_ERR,
+ 			"%s: Unable to bind to port %s: %s",
+@@ -818,7 +839,7 @@
+ #ifdef BSD4_4_SOCKADDR
+ 		     cliaddr.sa.sa_len == 0 ||
+ #endif
+-		     cliaddr.sa.sa_family != L_family))
++		     (L_family != AF_UNSPEC && cliaddr.sa.sa_family != L_family)))
+ 		{
+ 			(void) closesocket(connfd);
+ 			connfd = INVALID_SOCKET;
diff --git a/sendmail.spec b/sendmail.spec
new file mode 100644
index 0000000..bd9ec03
--- /dev/null
+++ b/sendmail.spec
@@ -0,0 +1,60 @@
+Name:          sendmail
+Version:       8.17.1
+Release:       1mamba
+Summary:       Implementation of the sendmail Mail Filter API
+Group:         System/Servers
+Vendor:        openmamba
+Distribution:  openmamba
+Packager:      Silvan Calarco <silvan.calarco@mambasoft.it>
+URL:           https://www.proofpoint.com/us/sendmail-open-source
+Source:        https://ftp.sendmail.org/sendmail.%{version}.tar.gz
+Source1:       libmilter-site.config.m4
+Patch0:        sendmail-8.17.1-fd-passing-libmilter.patch
+License:       Custom
+## AUTOBUILDREQ-BEGIN
+## AUTOBUILDREQ-END
+
+%description
+Implementation of the sendmail Mail Filter API
+
+%package -n libmilter-devel
+Group:         Development/Libraries
+Summary:       Development files for %{name}
+
+%description -n libmilter-devel
+This package contains libraries and header files for developing applications that use %{name}.
+
+#% debug_package
+
+%prep
+%setup -q
+%patch0 -p1 -b .fd-passing-libmilter
+cp %{SOURCE1} devtools/Site/site.config.m4
+
+%build
+%make -C libmilter
+
+%install
+[ "%{buildroot}" != / ] && rm -rf "%{buildroot}"
+
+install -d -m0755 %{buildroot}%{_libdir}
+%makeinstall -C libmilter \
+   INCOWN=`id -u` INCGRP=`id -g` INCMODE=0644 \
+   LIBOWN=`id -u` LIBGRP=`id -g` LIBMODE=0644 \
+   LIBDIR=%{_libdir}
+
+%clean
+[ "%{buildroot}" != / ] && rm -rf "%{buildroot}"
+
+%files -n libmilter-devel
+%defattr(-,root,root)
+%dir %{_includedir}/libmilter
+%{_includedir}/libmilter/mfapi.h
+%{_includedir}/libmilter/mfdef.h
+%{_libdir}/libmilter.a
+%doc README
+%doc LICENSE
+
+%changelog
+* Sat Jan 28 2023 Silvan Calarco <silvan.calarco@mambasoft.it> 8.17.1-1mamba
+- package created using the webbuild interface