The Best mail.tm Alternative in 2026 (With a CLI, SDK, and Real Automation)

mail.tm has been a popular choice for developers who wanted something slightly more capable than a basic web-based temp mail service. Its REST API is clean, it offers custom domains, and it has been reliable enough for casual use. But in 2026, if you are using disposable email in any serious development or automation context, mail.tm leaves you with major gaps that have no workaround.

This post covers exactly what those gaps are, what FreeCustom.Email does differently, and how to migrate — including the CLI, SDKs, OTP extraction, WebSocket streaming, and automation integrations that mail.tm does not have.

What mail.tm Gets Right

To be fair: mail.tm is not a bad service. Its API is well-documented, it supports creating accounts and reading messages, and the web UI is decent. For developers who need a quick disposable address for manual testing, it is usable.

But "usable for manual testing" is a low bar. Here is where it stops:

mail.tm has no CLI, no official SDK for any language, no OTP extraction, no WebSocket delivery, and no automation integrations. It is a REST API and a web UI. For anything beyond manually fetching emails, you are on your own.

The CLI Gap: Why It Matters More Than You Think

FreeCustom.Email ships fce — the only official CLI in the entire disposable email category. No other provider — mail.tm, Mailinator, Guerrilla Mail, Temp-Mail — has an installable, maintained CLI tool.

With mail.tm, the equivalent of a one-line inbox creation and watch requires you to:

1. Write your own HTTP client code

2. Parse the authentication response

3. Poll GET /messages in a loop

4. Parse the email body with regex to find the OTP

5. Handle errors, retries, and timeouts yourself

With fce, all of that is:

fce login    # once, browser-based, keychain-backed
fce dev      # inbox created + watching in real time

And OTP extraction:

fce otp dev-fy8x@ditcloud.info

────────────────────────────────────────────────
  OTP
────────────────────────────────────────────────

  OTP   ·  212342
  From  ·  noreply@myapp.com
  Subj  ·  Your verification code
  Time  ·  20:19:54

No regex. No custom code. No maintenance burden.

Install fce (All Platforms)

# macOS / Linux — shell script
curl -fsSL freecustom.email/install.sh | sh

# macOS / Linux — Homebrew
brew tap DishIs/homebrew-tap && brew install fce

# Windows — Scoop
scoop bucket add fce https://github.com/DishIs/scoop-bucket && scoop install fce

# Windows — Chocolatey
choco install fce

# All platforms — npm
npm install -g fcemail@latest

# All platforms — Go
go install github.com/DishIs/fce-cli@latest

Source code and all releases: github.com/DishIs/fce-cli
Latest release: github.com/DishIs/fce-cli/releases/latest

Authenticate once and your API key is saved to your OS keychain automatically — no manual token management, no re-authenticating when your key changes:

fce login
# Browser opens → sign in → done
# Keys auto-update with your plan

API Comparison: mail.tm vs FreeCustom.Email

Authentication

mail.tm:

# Create account
curl -X POST https://api.mail.tm/accounts \
  -d '{"address":"user@domain.ltd","password":"pass"}'

# Get JWT (must be refreshed)
curl -X POST https://api.mail.tm/token \
  -d '{"address":"user@domain.ltd","password":"pass"}'

FreeCustom.Email:

fce login   # once, browser-based, no manual JWT management
# Or for CI:
export FCE_API_KEY=fce_your_key_here

mail.tm requires you to create an account (with a password!) and manage a JWT. FreeCustom.Email uses a simple Bearer token that never expires unless you rotate it.

Creating an inbox

mail.tm:

# First create the account, get a token, then use it
curl https://api.mail.tm/accounts \
  -d '{"address":"test@domain.ltd","password":"pass123"}'
# → need to manage this account/password pair

FreeCustom.Email:

curl -X POST https://api2.freecustom.email/v1/inboxes \
  -H "Authorization: Bearer fce_your_key" \
  -d '{"inbox":"test@ditmail.info"}'
# Or simply:
fce inbox add random

Fetching messages

mail.tm:

curl https://api.mail.tm/messages \
  -H "Authorization: Bearer $JWT"
# Returns full message list — you must poll

FreeCustom.Email:

# Polling:
curl https://api2.freecustom.email/v1/inboxes/test@ditmail.info/messages \
  -H "Authorization: Bearer fce_your_key"

# Real-time WebSocket (Startup plan+):
fce watch test@ditmail.info
# → emails appear in < 200ms

OTP extraction

mail.tm:

No OTP extraction endpoint.
You must fetch the full email body and parse it yourself.

FreeCustom.Email:

curl "https://api2.freecustom.email/v1/inboxes/test@ditmail.info/otp" \
  -H "Authorization: Bearer fce_your_key"
# → { "success": true, "data": { "otp": "212342", "from": "...", ... } }

# Or via CLI:
fce otp test@ditmail.info

SDK Comparison

mail.tm has no official SDK. Community-maintained libraries exist but are unofficial, often outdated, and cover only basic message fetching.

FreeCustom.Email ships official, maintained SDKs:

JavaScript / TypeScript

npm install freecustom-email

import { FreecustomEmailClient } from 'freecustom-email';
const fce = new FreecustomEmailClient({ apiKey: process.env.FCE_API_KEY! });

await fce.inboxes.register('test@ditmail.info');
const otp = await fce.otp.waitFor('test@ditmail.info');
console.log(otp); // '212342'

Full TypeScript types, ESM + CJS dual build, auto-reconnect WebSocket, and typed error classes.

Python

pip install freecustom-email

from freecustom_email import FreeCustomEmail
import asyncio, os

fce = FreeCustomEmail(api_key=os.environ["FCE_API_KEY"])

async def main():
    await fce.inboxes.register("test@ditmail.info")
    otp = await fce.otp.wait_for("test@ditmail.info")
    print(otp)  # '212342'

asyncio.run(main())

Full type annotations, async + sync modes, dataclass response models.

Real-Time Delivery: mail.tm vs FCE WebSocket

This is one of the most significant differences for anyone building test automation.

mail.tm is polling-only. You call GET /messages repeatedly and wait for something to appear. In a CI pipeline with a tight timeout, you might poll 30 times over 60 seconds before giving up.

FreeCustom.Email delivers emails via WebSocket on Startup plan+. The email arrives in your terminal (or SDK callback) in under 200ms from the moment it hits the SMTP server:

fce watch test@ditmail.info
# Emails appear instantly as they arrive
# Auto-reconnects if connection drops

In a CI pipeline, this means the difference between a 30-second wait loop and a 200ms response. See How to Automate Email Verification Testing in CI/CD Pipelines (2026) for full CI examples.

Migration: From mail.tm to FreeCustom.Email

Migration is straightforward. The API patterns are similar — both are REST with Bearer auth.

Step 1: Get an FCE account and API key

# Install CLI
curl -fsSL freecustom.email/install.sh | sh

# Login — creates API key automatically, saves to keychain
fce login

Step 2: Replace account creation with inbox registration

Before (mail.tm):

// Create account + get JWT
const accountRes = await fetch('https://api.mail.tm/accounts', {
  method: 'POST',
  body: JSON.stringify({ address: inbox, password: 'pass123' }),
});
const tokenRes = await fetch('https://api.mail.tm/token', {
  method: 'POST',
  body: JSON.stringify({ address: inbox, password: 'pass123' }),
});
const { token } = await tokenRes.json();

After (FreeCustom.Email SDK):

const fce = new FreecustomEmailClient({ apiKey: process.env.FCE_API_KEY });
await fce.inboxes.register(inbox);
// No JWT management needed

Step 3: Replace message polling with OTP extraction

Before (mail.tm):

// Poll for messages
let otp = null;
for (let i = 0; i < 30 && !otp; i++) {
  await sleep(2000);
  const res = await fetch('https://api.mail.tm/messages', {
    headers: { Authorization: `Bearer ${token}` },
  });
  const { 'hydra:member': messages } = await res.json();
  if (messages.length > 0) {
    const body = messages[0].text;
    const match = body.match(/\b(\d{6})\b/);
    otp = match?.[1];
  }
}

After (FreeCustom.Email SDK):

const otp = await fce.otp.waitFor(inbox, { timeout: 30_000 });
// Done. No polling loop, no regex.

Step 4: Replace cleanup

Before (mail.tm):

await fetch(`https://api.mail.tm/accounts/${accountId}`, {
  method: 'DELETE',
  headers: { Authorization: `Bearer ${token}` },
});

After (FreeCustom.Email):

await fce.inboxes.unregister(inbox);
// Or: fce inbox remove inbox@ditmail.info

Automation Ecosystem: What mail.tm Has None Of

Beyond the API and CLI, FreeCustom.Email is the only disposable email service with a genuine automation ecosystem — something mail.tm completely lacks:

For the full automation guide: freecustom.email/api/automation
For AI agent workflows: AI Agent Email Automation with OpenClaw and n8n (2026)

Pricing Comparison

Full FCE pricing: freecustom.email/api/pricing

Use Case Cheat Sheet

Frequently Asked Questions

Is mail.tm still maintained? As of March 2026, mail.tm's API is operational but has not seen significant developer tooling improvements. No CLI, SDK, WebSocket, or OTP extraction has been added. The API remains polling-only.

Does FreeCustom.Email support the same domains as mail.tm? FCE has its own domain network. Run fce domains to list all available on your plan. Custom domain registration is available on Growth and above.

Can I use FreeCustom.Email without the CLI? Yes. The REST API, JS SDK, and Python SDK all work independently of the CLI. The CLI is an additional tool, not a requirement.

Is there a mail.tm SDK I can just swap out? No official mail.tm SDK exists. If you are using a community library, you can replace it with npm install freecustom-email or pip install freecustom-email and update the API calls as shown in the migration section above.

Does FCE have rate limits? Yes. Free: 1 req/sec. Developer: 10/sec. Startup: 25/sec. Growth: 50/sec. Enterprise: 100/sec. For automation at scale, Startup or Growth is recommended.

What is the uptime SLA? FreeCustom.Email targets 99.9% uptime. Current status: status.freecustom.email.

Does FCE work for non-developer personal use too? Yes. FreeCustom.Email started as a consumer temp mail service. See Best Disposable Email for Free Trials, Temp Mail for Instagram, and Is Temp Mail Safe? for non-developer use cases.

Summary

mail.tm is a reasonable REST API for basic disposable email access. But if you need any of the following, you have already outgrown it:

• A CLI you can actually run in a terminal

• OTP extraction without writing regex

• Real-time email delivery (not polling)

• Official SDKs for TypeScript or Python

• Playwright or Selenium test integration

• CI/CD pipelines that can run in parallel

• AI agent automation

• n8n, Make, or Zapier visual workflows

All of those are available in FreeCustom.Email today. The free tier requires no credit card and gives you 5,000 requests per month to evaluate everything before committing to a paid plan.

Related reading

• Why FreeCustom.Email Is the Only Disposable Email API With an Official CLI (2026)

• FreeCustom.Email vs Mailinator vs Guerrilla Mail: API Comparison (2026)

• 10 Best Temp-Mail Alternatives in 2026

• Best Temporary Email Services in 2026

• How to Automate Email Verification Testing in CI/CD Pipelines (2026)

• AI Agent Email Automation with OpenClaw and n8n (2026)

• Disposable Email for Signup Automation (2026)

• How to Receive OTP Without Using Your Real Email (2026)

• Temp Mail for Business

• Best Disposable Email for Free Trials

• Is Temp Mail Safe?

• Private or Custom Domains

• fce CLI documentation

• API documentation

• API Playground

• fce CLI on GitHub

• Latest CLI release