Free Email Sandbox — No Signup Needed
Get an SMTP inbox in one click. Test transactional emails from your app, see them arrive in real time, inspect headers and HTML — all without ever signing up.
Spin up a temporary inbox in 1 second
Send up to 20 emails per sender every 30 minutes through our SMTP server, capture them in your private sandbox, and inspect every detail. No account required — a faster, privacy-first way to test transactional email.
See how MailDog compares to Mailtrap and Mailgun →
Want unlimited inboxes, retention & a full dashboard? Create a free account →
Already own a domain? You already own email.
Maildog turns the domain you already own into real professional inboxes — full SMTP & IMAP with SPF, DKIM & DMARC configured for you. No Google Workspace, no separate mail service to buy. Set up in minutes.
Trusted by teams everywhere
One platform for testing and sending real email
Most tools make you choose: a throwaway environment for transactional email testing, or a separate provider for custom domain email hosting. MailDog does both. Spin up a free SMTP sandbox in one second to capture and inspect outgoing mail, then host production email on your own domain with automatic DKIM and DMARC configuration for maximum email deliverability.
| Feature | MailDog | Typical alternatives |
|---|---|---|
| Free SMTP sandbox | ||
| No signup required | ||
| Real-time email inspection | ||
| Custom domain email hosting | ||
| Full SMTP & IMAP access | ||
| Automatic SPF, DKIM & DMARC |
Switching providers? MailDog vs Mailtrap · MailDog vs Mailgun
One Platform, Complete Email Solution
Everything you need to send, receive, and manage professional email with your custom domain.
Email Hosting
Host professional email on your custom domain. Create unlimited accounts with full SMTP & IMAP access.
Learn moreSMTP & IMAP
Reliable email delivery with SMTP for sending and IMAP for receiving. Works with any email client.
Learn moreDNS & Security
Auto-configure SPF, DKIM & DMARC records. Enterprise-grade email authentication and encryption.
Learn moreActionable Email Insights
Monitor your email performance with real-time dashboards, delivery tracking, and detailed logs. Know exactly when your emails are delivered.
99.8%
Delivery Rate
12.4k
Emails Sent
5
Domains
DNS Verification Status
Get Started in 3 Simple Steps
From domain registration to sending your first email — everything is guided and automated.
Add Your Domain
Register your custom domain in the dashboard. We support any domain you own — no limitations.
Configure DNS
Follow our guided setup. We auto-verify MX, SPF, DKIM, and DMARC records in real-time.
Start Sending
Create email accounts and connect with any client — Outlook, Gmail, Apple Mail, or Thunderbird.
Loved by Teams Everywhere
“MailDog made it incredibly easy to set up professional email for our startup. We were sending from our domain within 20 minutes.”
Sarah Chen
CTO @ Launchpad
“The DKIM and SPF setup was automated, and our email deliverability improved immediately. Night and day difference from our old provider.”
Marcus Rodriguez
Founder @ BrightPath
“Managing email accounts across multiple domains used to be a headache. MailDog's dashboard makes it simple to manage everything.”
Emily Watson
Operations Lead @ Nextera
Frequently Asked Questions
Everything you need to know about the free SMTP sandbox and custom-domain email hosting.
What is an SMTP sandbox?
An SMTP sandbox is a safe testing environment that captures the emails your application sends without delivering them to real recipients. MailDog gives you real SMTP credentials instantly, so you can send test messages from any app and inspect their HTML, headers, and spam score in real time.
Do I need to sign up to use the free SMTP sandbox?
No. MailDog's SMTP sandbox requires no account or signup. Click “Launch Free Sandbox” to get real SMTP credentials instantly. You can send up to 20 emails per sender every 30 minutes, and your inbox is automatically deleted after 24 hours.
How do I set up email for my custom domain?
After signing up, add your domain in the dashboard. We'll provide you with the exact DNS records (MX, SPF, DKIM, DMARC) to add at your domain registrar. Our system automatically verifies your records — most setups are complete within minutes.
Which email clients are supported?
MailDog works with all standard email clients including Outlook, Gmail (via IMAP), Apple Mail, Thunderbird, and any client that supports SMTP/IMAP. We provide step-by-step setup guides for each client.
What are SPF, DKIM, and DMARC?
These are email authentication protocols that protect your domain from spoofing and improve deliverability. SPF verifies which servers can send email for your domain, DKIM adds a digital signature to your emails, and DMARC tells receiving servers how to handle authentication failures. MailDog configures all three automatically.
Can I create multiple email accounts on one domain?
Yes! Depending on your plan, you can create multiple email accounts on each domain. Each account gets its own login credentials and can be configured independently in any email client.
What SMTP and IMAP settings do I need?
SMTP server: mail.maildog.io, Port 587 with STARTTLS. IMAP server: mail.maildog.io, Port 993 with SSL/TLS. Use your full email address as the username and the password you set during account creation.
How long does DNS propagation take?
DNS changes typically propagate within 5-30 minutes, though in some cases it can take up to 24-48 hours depending on your domain registrar and DNS provider. Our dashboard shows real-time verification status so you know exactly when your records are active.
24/7 Expert Support
Our team of email engineers and deliverability specialists are always available to help you get the most out of MailDog.