diff --git a/docker/Dockerfile b/docker/Dockerfile
index b3d64e0..341843f 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -17,6 +17,9 @@ COPY license.html /opt/rustmailer/
 # Set proper permissions
 RUN chmod +x /opt/rustmailer/rustmailer
 
+# Install ca-certificates to ensure HTTPS certificate verification works correctly
+RUN apt update && apt install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+
 # Create data directory
 RUN mkdir -p /data