diff --git a/README.md b/README.md
index ad4e620..3a71175 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 > The minimalistic email relay for contact forms and more!
 
 This is basically a minimal self-hosted open source alternative to [Formspree](https://formspree.io/) and [SendGrid](https://sendgrid.com/).  
-Unlike other mail services (that often gives you an API key), this self-hosted mail service is designed to be accessed directly from a frontend.
+Unlike other mail services (that often gives you an API key for backends), this self-hosted mail service is designed to be accessed directly from a frontend.
 
 ### Features
 - Access via API or HTML form + redirect
@@ -29,6 +29,7 @@ cd mailform
 docker build -t Feuerhamster/mailform .
 docker run Feuerhamster/mailform
   -e PORT=3000
+  -e PROXY=true
   -v /your/custom/path /app/targets
 ```
 
@@ -45,8 +46,12 @@ npm run start
 
 ## ⚙️Configuration
 ### Application
-To configure the port, simply set the environment variable `PORT` to the port you want to have.
-If you want to have your targets in a different directory, you can change that in the `TARGETS_DIR` environment variable.
+MailForm can be configured using environment variables.
+
+**Environment variables:**
+- `PORT` The port on which the application starts. If not provided, a random port will be selected.
+- `TARGETS_DIR` Path to the directory with your target files. Default is `/targets` of the project root.
+- `PROXY` A boolean that enables the "trust proxy" option of Express. **Enable this if you're using MailForm behind a reverse proxy like NGINX!** Default value is false.
 
 ### Targets
 Targets are your different endpoints each with its own rate limits and smtp provider.
diff --git a/src/main.ts b/src/main.ts
index c2593cb..ecbc938 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -6,8 +6,13 @@ import routes from "./router";
 
 // Start express app
 const port = process.env.PORT || 0;
+const trustProxy: boolean = (process.env.PROXY === "true");
+
 const app: Application = express();
 
+app.set("trust proxy", trustProxy);
+app.set("x-powered-by", false);
+
 // Middlewares
 app.use(express.json());
 app.use(express.urlencoded({ extended: true }));
diff --git a/src/services/email.ts b/src/services/email.ts
index f69a387..9cb8373 100644
--- a/src/services/email.ts
+++ b/src/services/email.ts
@@ -7,7 +7,7 @@ export class EmailService {
     private static targetTransports: Map<string, Transporter> = new Map<string, Transporter>();
 
     /**
-     * Register a mail target in the email service
+     * Register a target in the email service
      * @param targetName (file-)name of an existing and loaded target
      * @param smtpURL A valid SMTP(S) URL
      */
diff --git a/src/services/rateLimiter.ts b/src/services/rateLimiter.ts
index 3b9c353..db8ef6d 100644
--- a/src/services/rateLimiter.ts
+++ b/src/services/rateLimiter.ts
@@ -5,6 +5,11 @@ export class RateLimiter {
 
     private static limiters: Map<string, RateLimiterMemory> = new Map<string, RateLimiterMemory>();
 
+    /**
+     * Register a target in the rate limiter service
+     * @param targetName Name of the target
+     * @param limits Rate limit configuration for target
+     */
     public static registerTarget(targetName: string, limits: TargetRateLimit): void {
 
         this.limiters.set(targetName, new RateLimiterMemory({
@@ -14,6 +19,11 @@ export class RateLimiter {
 
     }
 
+    /**
+     * Consume one point of a target's rate limiter
+     * @param target (file-)name of a target
+     * @param identifier Rate limiter identifier (ip address)
+     */
     public static async consume(target, identifier): Promise<boolean> {
 
         let rateLimiter: RateLimiterMemory = this.limiters.get(target);