diff --git a/go.mod b/go.mod
index a12f908..0402218 100644
--- a/go.mod
+++ b/go.mod
@@ -6,5 +6,6 @@ require (
 	github.com/alash3al/go-smtpsrv v0.0.0-20220704173150-cdaad3f3f582 // indirect
 	github.com/go-resty/resty/v2 v2.3.0
 	github.com/miekg/dns v1.1.50 // indirect
+	github.com/zaccone/spf v0.0.0-20170817004109-76747b8658d9 // indirect
 	golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9 // indirect
 )
diff --git a/main.go b/main.go
index b7b6b4f..8e37638 100644
--- a/main.go
+++ b/main.go
@@ -6,12 +6,14 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"net"
 	"net/mail"
 	"strings"
 	"time"
 
 	"github.com/alash3al/go-smtpsrv"
 	"github.com/go-resty/resty/v2"
+	"github.com/zaccone/spf"
 )
 
 func main() {
@@ -27,7 +29,17 @@ func main() {
 				return errors.New("Cannot read your message: " + err.Error())
 			}
 
-			spfResult, _, _ := c.SPF()
+			// replace source IP with the one from Received header because there is an additional MTA in front
+			var spfResult spf.Result = spf.None
+			receivedAddr := msg.Header.Get("Received")
+			if receivedAddr == "" {
+				spfResult, _, _ = c.SPF()
+			} else {
+				_, host, err := smtpsrv.SplitAddress(c.From().Address)
+				if err == nil {
+					spfResult, _, _ = spf.CheckHost(net.ParseIP(receivedAddr), host, c.From().Address)
+				}
+			}
 
 			jsonData := EmailMessage{
 				ID:            msg.MessageID,