diff --git a/go.mod b/go.mod
index 65f8503c..6c27a618 100644
--- a/go.mod
+++ b/go.mod
@@ -17,7 +17,7 @@ require (
 	github.com/dghubble/oauth1 v0.7.2
 	github.com/go-telegram-bot-api/telegram-bot-api v4.6.4+incompatible
 	github.com/line/line-bot-sdk-go v7.8.0+incompatible
-	github.com/mailgun/mailgun-go/v4 v4.8.2
+	github.com/mailgun/mailgun-go/v4 v4.9.0
 	github.com/pkg/errors v0.9.1
 	github.com/plivo/plivo-go/v7 v7.29.0
 	github.com/sendgrid/sendgrid-go v3.12.0+incompatible
diff --git a/go.sum b/go.sum
index 21e46f62..449d0493 100644
--- a/go.sum
+++ b/go.sum
@@ -208,8 +208,8 @@ github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/line/line-bot-sdk-go v7.8.0+incompatible h1:Uf9/OxV0zCVfqyvwZPH8CrdiHXXmMRa/L91G3btQblQ=
 github.com/line/line-bot-sdk-go v7.8.0+incompatible/go.mod h1:0RjLjJEAU/3GIcHkC3av6O4jInAbt25nnZVmOFUgDBg=
-github.com/mailgun/mailgun-go/v4 v4.8.2 h1:52uaKBnTAaVtKFGtLwUSnpUzQKX1z8RfwYsBaON0l5s=
-github.com/mailgun/mailgun-go/v4 v4.8.2/go.mod h1:FJlF9rI5cQT+mrwujtJjPMbIVy3Ebor9bKTVsJ0QU40=
+github.com/mailgun/mailgun-go/v4 v4.9.0 h1:wRbxvVQ5QObFewLxc1uVvipA16D8gxeiO+cBOca51Iw=
+github.com/mailgun/mailgun-go/v4 v4.9.0/go.mod h1:FJlF9rI5cQT+mrwujtJjPMbIVy3Ebor9bKTVsJ0QU40=
 github.com/mattn/go-colorable v0.1.12 h1:jF+Du6AlPIjs2BiUiQlKOX0rt3SujHxPnksPKZbaA40=
 github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
 github.com/mattn/go-isatty v0.0.14 h1:yVuAays6BHfxijgZPzw+3Zlu5yQgKGP2/hcQbHb7S9Y=