Do I need my own mail server?

No. Any SMTP login works, including the Gmail or Zoho account you already have. Neuctra Mailer connects to it and sends on your behalf.

Is it safe to put the API key in frontend code?

Yes, with the public key's limits on. List your websites, set allowed recipients (for a contact form, only your own address), keep the rate limits and optionally require a Cloudflare Turnstile captcha. A copied key then can't be used to spam. Send from your server with the separate server key, which browsers can't use.

How is my SMTP password stored?

It is encrypted with AES-256-GCM before it is saved and is never sent back to the browser. The dashboard only shows whether a password is set.

Plain text, HTML or both, with to, cc, bcc and reply-to. One email can go to up to 50 recipients.

Can I collect subscribers and welcome them?

Yes. Create lists, add people from your forms with mailer.subscribe(), and design emails with templates. Turn on a list's welcome email and every new subscriber gets it right away.

How do unsubscribes work?

Every marketing email includes an unsubscribe link, plus the header that lets Gmail, Outlook and Apple Mail show their own one-click Unsubscribe button. People who leave go on the service's do-not-send list and get no more marketing email from any of your lists.

How do you keep my emails out of spam?

Emails go out through your own SMTP account with one-click unsubscribe headers. Addresses that bounce or unsubscribe are never emailed again, a new service is warmed up with a daily cap, and rate limits stop sudden bursts. On your side, send from your own domain and set up SPF, DKIM and DMARC with your mail provider.

Why did my test email time out?

Usually your network or host blocks outgoing SMTP ports 465 and 587. Try another network, or check that your hosting provider allows SMTP traffic.

Bring your own SMTP · Now with lists and welcome emails

SendemailfromanyappwithyourownSMTP.

Connect the Gmail, Zoho or SES account you already have. Then send from your frontend or backend with one SDK call, grow email lists, send to them, and welcome new subscribers from one dashboard.

Create your accountSee how it works

No mail server to run
Browser and Node.js
Set up in about two minutes

Try it: send a test emailLive demo

Your app

Neuctra Mailer

Your SMTP

Press send to watch the trip

Sent in this demo

Nothing yet. Press Send email.

Works with the mail account you already have

Gmail
Google Workspace
Zoho Mail
Amazon SES
Outlook
Microsoft 365
Brevo
Mailgun
Any SMTP server
Gmail
Google Workspace
Zoho Mail
Amazon SES
Outlook
Microsoft 365
Brevo
Mailgun
Any SMTP server

SDK call to send

mailer.send() from any JavaScript app

Recipients per email

Across to, cc and bcc

0-bit

AES-GCM encryption

For SMTP passwords and API keys

SDK dependencies

Browser, React, Next.js and Node 18+

How it works

Live in three steps

No mail server to run and no template language to learn. Bring the SMTP account you already have.

01
Create a service
One service per app. Name it and you get a service ID and an API key, ready to copy.
service_7f3a · My Shop
02
Connect your SMTP login
Enter the host, port and login from your mail provider, then send a test email to confirm it works.
smtp.gmail.com : 465 · Verified
03
Call mailer.send()
Install @neuctra/mailer and send from a React form, an API route or a background job.
npm install @neuctra/mailer

Features

Built for the moment something goes wrong

Sending is the easy part. Keeping your key and your SMTP account safe is where it counts.

Limits that make a copied key useless

A key in browser code can be copied, and scripts can fake the website. Rate limits, allowed recipients and a captcha stop it from being used to spam through your SMTP account.

Emails per minute: 30 per service, for both keys
Emails per day: 500 keep it under your provider's limit
Allowed recipients: [email protected] a copied key can't email anyone else
Captcha: Cloudflare Turnstile stops bots on your forms
Server key: nm_sk_... refused from browsers

Keys locked to your websites

List the sites allowed to use your public key. Other websites are refused.

https://myshop.com

https://admin.myshop.com

http://localhost:3000

https://other-site.com403

Rotate keys in one click

Leaked a key? Make a new one. The old key stops working right away.

nm_7f3a91c2e8b0…47f3

Try it: press Rotate.

Passwords encrypted at rest

SMTP passwords and API keys are encrypted with AES-256-GCM and never sent back to the browser.

SMTP password••••••••••

Errors that say what to fix

Wrong password or blocked port? You get a plain hint next to the raw SMTP error.

SMTP login failed

Check the username and password. Gmail needs an App Password.

535-5.7.8 Username and Password not accepted

Email marketing

More than transactional email

The same SMTP account that sends your receipts can reach your subscribers. Lists, templates, sending and welcome emails are built in.

Grow lists straight from your forms

Create a list in the dashboard, then add people from your signup or newsletter form with one SDK call.

mailer.subscribe() and mailer.unsubscribe()
Add and edit contacts in the dashboard
Duplicate signups are handled for you

Newsletter

Subscribed

JCJane Cooper[email protected] New
OHOmar Haddad[email protected]1 h ago
LPLee Park[email protected]Yesterday

await mailer.subscribe({
  listId, email: "[email protected]", name: "Jane"
});

For developers

Same SDK in the browser and on the server

Send a contact form straight from React, or an order email from your API. Every call works the same way.

npm install @neuctra/mailer

Browser, React, Next.js and Node 18+
No dependencies
TypeScript types included
Text, HTML, cc, bcc and reply-to

What each error status means
400	Something is wrong with the email itself
401	Wrong API key, service ID or name
403	Service paused, or website not allowed
502	Your SMTP server refused it, and why

app/contact/form.jsx

1const mailer = new NeuctraMailer({
2  serverUrl: process.env.NEXT_PUBLIC_MAILER_URL,
3  serviceId: process.env.NEXT_PUBLIC_MAILER_SERVICE_ID,
4  serviceName: process.env.NEXT_PUBLIC_MAILER_SERVICE_NAME,
5  apiKey: process.env.NEXT_PUBLIC_MAILER_API_KEY,
6});
7
8async function handleSubmit(form) {
9  await mailer.send({
10    to: "[email protected]",
11    replyTo: form.email,
12    subject: `New message from ${form.name}`,
13    text: form.message,
14  });
15}

Use cases

One service for every email your app sends

From a single contact form to a growing newsletter, it all goes out through the account you trust.

01
Contact forms
Send form messages to your inbox straight from the browser, with reply-to set to the visitor.
02
Orders and receipts
Confirmations, shipping updates and invoices from your API, with a bcc copy for your records.
03
Passwords and sign-in
Reset links and sign-in codes, sent the moment someone asks for them.
04
Signup lists
Collect subscribers from your forms and welcome each one automatically.
05
Announcements
Send a template to the people you pick in a list, and see who got it and who is still pending.
06
Team alerts
New signups, failed payments or errors, sent to your team from any job or script.

FAQ

Questions, answered

Something else? Create an account and try it with a test email. It takes about two minutes.

No. Any SMTP login works, including the Gmail or Zoho account you already have. Neuctra Mailer connects to it and sends on your behalf.
Yes, with the public key's limits on. List your websites, set allowed recipients (for a contact form, only your own address), keep the rate limits and optionally require a Cloudflare Turnstile captcha. A copied key then can't be used to spam. Send from your server with the separate server key, which browsers can't use.
It is encrypted with AES-256-GCM before it is saved and is never sent back to the browser. The dashboard only shows whether a password is set.
Plain text, HTML or both, with to, cc, bcc and reply-to. One email can go to up to 50 recipients.
Yes. Create lists, add people from your forms with mailer.subscribe(), and design emails with templates. Turn on a list's welcome email and every new subscriber gets it right away.
Every marketing email includes an unsubscribe link, plus the header that lets Gmail, Outlook and Apple Mail show their own one-click Unsubscribe button. People who leave go on the service's do-not-send list and get no more marketing email from any of your lists.
Emails go out through your own SMTP account with one-click unsubscribe headers. Addresses that bounce or unsubscribe are never emailed again, a new service is warmed up with a daily cap, and rate limits stop sudden bursts. On your side, send from your own domain and set up SPF, DKIM and DMARC with your mail provider.
Usually your network or host blocks outgoing SMTP ports 465 and 587. Try another network, or check that your hosting provider allows SMTP traffic.

Ready when you are

Send your first email today

Create a service, add your SMTP login and send a test. It takes about two minutes.

Create your accountSign in

SendemailfromanyappwithyourownSMTP.

Live in three steps

Create a service

Connect your SMTP login

Call mailer.send()