diff --git a/go.mod b/go.mod
index f175a65..a595d1b 100644
--- a/go.mod
+++ b/go.mod
@@ -2,7 +2,7 @@ module github.com/decke/smtprelay
 
 require (
 	github.com/DeRuina/timberjack v1.4.1
-	github.com/chrj/smtpd v0.3.1
+	github.com/chrj/smtpd v0.4.0
 	github.com/fsnotify/fsnotify v1.9.0
 	github.com/google/uuid v1.6.0
 	github.com/peterbourgon/ff/v3 v3.4.0
diff --git a/go.sum b/go.sum
index e9a0cff..73b97a9 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 github.com/DeRuina/timberjack v1.4.1 h1:JftM5HN/ITKehAXjtdbGqN5XZIS1biHm7VSjU0Qbtqg=
 github.com/DeRuina/timberjack v1.4.1/go.mod h1:RLoeQrwrCGIEF8gO5nV5b/gMD0QIy7bzQhBUgpp1EqE=
-github.com/chrj/smtpd v0.3.1 h1:kogHFkbFdKaoH3bgZkqNC9uVtKYOFfM3uV3rroBdooE=
-github.com/chrj/smtpd v0.3.1/go.mod h1:JtABvV/LzvLmEIzy0NyDnrfMGOMd8wy5frAokwf6J9Q=
+github.com/chrj/smtpd v0.4.0 h1:DPJY9XxJngESsV1O/GKeydN6c+iuV1dglW/dw0VlxFY=
+github.com/chrj/smtpd v0.4.0/go.mod h1:zEP61gNDlWp/jdUqBcq/ykIbgOERyRvwfMsRLl3h9gM=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fortytw2/leaktest v1.3.0 h1:u8491cBMTQ8ft8aeV+adlcytMZylmA5nnwwkRZjI8vw=