diff --git a/go.mod b/go.mod
index 594dc75..45b082e 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/emersion/go-smtp v0.21.3
 	github.com/go-ozzo/ozzo-validation/v4 v4.3.0
 	github.com/kelseyhightower/envconfig v1.4.0
-	github.com/mailgun/mailgun-go/v4 v4.18.1
+	github.com/mailgun/mailgun-go/v4 v4.18.5
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.20.5
 	github.com/sirupsen/logrus v1.9.3
diff --git a/go.sum b/go.sum
index c8d5cff..408808e 100644
--- a/go.sum
+++ b/go.sum
@@ -35,8 +35,8 @@ github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/mailgun/errors v0.3.0 h1:g8R8lodkwqk5WIVMAClyUqt0PSd5JTVgobB+H7C2sLs=
 github.com/mailgun/errors v0.3.0/go.mod h1:+ltknP+jhv3gZ1StKY6ugoQECcPxDCaSdmYesqTZcLQ=
-github.com/mailgun/mailgun-go/v4 v4.18.1 h1:ShNH/wzj7albTF/6le011FF+DGMd3azcSKL4iO9AgeI=
-github.com/mailgun/mailgun-go/v4 v4.18.1/go.mod h1:+d4FCswFAukgYc1XtKK2IxOYaVxjVm8AN2z/5TBiT8M=
+github.com/mailgun/mailgun-go/v4 v4.18.5 h1:wZnTutW/fzxNyJVBMa6O4LLGW/hO+IGfKpuqBT4nbVs=
+github.com/mailgun/mailgun-go/v4 v4.18.5/go.mod h1:+d4FCswFAukgYc1XtKK2IxOYaVxjVm8AN2z/5TBiT8M=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=