diff --git a/apps/api/src/docker/mailserver.ts b/apps/api/src/docker/mailserver.ts
index 4e150bd..6235e95 100644
--- a/apps/api/src/docker/mailserver.ts
+++ b/apps/api/src/docker/mailserver.ts
@@ -4,6 +4,18 @@ import { hostedMailboxSchema } from "../lib/validation";
 import { runDocker } from "./runner";
 
 const MAILDIR_FOLDER = "INBOX";
+const infrastructureErrorPatterns = [
+  /cannot connect to the docker daemon/i,
+  /permission denied/i,
+  /no such container/i,
+  /is not running/i,
+  /executable file not found/i,
+  /no such file or directory/i,
+  /command not found/i
+];
+
+const looksLikeInfrastructureFailure = (output: string): boolean =>
+  infrastructureErrorPatterns.some((pattern) => pattern.test(output));
 
 const localPartRegex = /^[A-Z0-9.!#$%&'*+/=?^_`{|}~-]{1,64}$/i;
 
@@ -29,6 +41,11 @@ export const authenticateMailbox = async (email: string, password: string): Prom
     { allowNonZero: true }
   );
 
+  const combinedOutput = `${result.stdout}\n${result.stderr}`.trim();
+  if (result.exitCode !== 0 && looksLikeInfrastructureFailure(combinedOutput)) {
+    throw new HttpError(502, "Mail authentication backend is unavailable.");
+  }
+
   return result.exitCode === 0;
 };
 
@@ -85,4 +102,3 @@ export const removeForwardingAlias = async (sourceEmail: string, targetEmail: st
 };
 
 export const getSupportedFolder = (): string => MAILDIR_FOLDER;
-
diff --git a/apps/api/src/lib/config.ts b/apps/api/src/lib/config.ts
index 082cdb4..b3cea24 100644
--- a/apps/api/src/lib/config.ts
+++ b/apps/api/src/lib/config.ts
@@ -1,6 +1,10 @@
 import { resolve } from "node:path";
 import { z } from "zod";
 
+const normalizedEnv = Object.fromEntries(
+  Object.entries(Bun.env).map(([key, value]) => [key, value === "" ? undefined : value])
+);
+
 const splitList = (value: string | undefined, fallback: string): string[] =>
   (value ?? fallback)
     .split(",")
@@ -35,7 +39,7 @@ const envSchema = z.object({
   TOTP_ENCRYPTION_KEY: z.string().optional()
 });
 
-const raw = envSchema.parse(Bun.env);
+const raw = envSchema.parse(normalizedEnv);
 
 if ((raw.APP_ADMIN_EMAIL && !raw.APP_ADMIN_PASSWORD) || (!raw.APP_ADMIN_EMAIL && raw.APP_ADMIN_PASSWORD)) {
   throw new Error("APP_ADMIN_EMAIL and APP_ADMIN_PASSWORD must be provided together.");
@@ -69,4 +73,3 @@ export const config = {
   adminPassword: raw.APP_ADMIN_PASSWORD ?? null,
   totpEncryptionKey: raw.TOTP_ENCRYPTION_KEY ?? null
 } as const;
-