Help Center
Find answers to common questions about Mail.td — email addresses, inboxes, API, domains, and more.
Getting Started
What is Mail.td?
Mail.td is an email testing platform for developers. It provides instant on-demand inboxes for receiving emails, testing account verification flows, and integrating email reception into your applications via REST API, WebSocket events, webhooks, and SMTP Sandbox.
How do I get an email address?
Visit mail.td and click "Get Email Address" to instantly generate a free temp mail address. You can specify a custom username or generate a random one. Select a domain and your temp mail inbox is ready immediately.
Can I create a password-protected temp mail?
Yes. When you create a temp mail on mail.td, you can set a custom username and password, then log back in from any device to access the same mailbox. Passwords are encrypted in your browser before upload — the server never sees plaintext. All connections are TLS-encrypted, so only you can access your password and emails.
How long does an inbox last?
Emails: retained for 7 days by default; after expiration, all emails, attachments, and raw .eml files are permanently deleted.
Mailbox accounts: deleted after 3 months without login.
Pro members: unaffected while subscribed; after downgrade, if not resubscribed within 90 days, all mailboxes under the account are permanently deleted.
Do I need a Pro account?
You can get a free email address and start receiving emails immediately. A Pro account is optional and unlocks additional features like custom domains, API tokens, webhooks, and SMTP Sandbox.
Email Addresses & Authentication
How do I get started?
Visit mail.td and click "Get Email Address" to get a free inbox instantly, or register for a Pro account at mail.td/pro/register for advanced features.
What is the difference between Free and Pro?
Free email addresses get basic inbox access with up to 40 MB storage and 1,000 API operations per month. Pro accounts unlock 100,000 API operations per month, custom domains, webhooks, API tokens, SMTP Sandbox, and 50 MB storage per mailbox.
Mailboxes & Emails
What are the email limits?
Each mailbox has a total storage quota of 40 MB. The SMTP gateway accepts emails up to 15 MB per message with up to 5 recipients.
Can I receive emails in real time?
Yes. Mail.td supports WebSocket connections for real-time push notifications when a new email arrives. If WebSocket is unavailable, the client falls back to polling every 10 seconds.
Does Mail.td receive email attachments?
Yes. Mail.td accepts images, PDFs, archives, Office documents, and other common file types. Total email size is capped at 15 MB per message, and because attachments are base64-encoded in transit, the usable payload is about 10 MB. Download attachments individually from the inbox UI or via the REST API; the full message is also available as a .eml file.
API & Tokens
How does API authentication work?
Pro users can create API tokens for programmatic access. Tokens are passed via the Authorization header. Tokens are stored as SHA-256 hashes — Mail.td never stores your token in plaintext.
What can I do with the API?
The API provides endpoints for managing mailboxes, listing and reading emails, downloading attachments, managing custom domains, webhooks, and API tokens. Interactive API documentation is available at the /api/docs endpoint.
What happens if I lose my API token?
API tokens are only displayed once at creation and cannot be retrieved later. If you lose a token, revoke it and create a new one.
Custom Domains
How do I add a custom domain?
Go to Pro Dashboard > Domains, click "Add Domain" and enter your domain. Then configure the required DNS records:
1. TXT record for domain verification
2. MX record pointing to Mail.td's SMTP server
How long does domain verification take?
Domain verification depends on your DNS provider's propagation speed — typically a few minutes to 48 hours.
How do custom domains work?
Custom domains work as catch-all — any email sent to any address at your verified domain will be received automatically. You don't need to create individual mailboxes for each address.
Webhooks
How do webhooks work?
When a new email arrives for a Pro user's mailbox, Mail.td sends an HTTP POST request to your configured webhook URL. The payload includes email metadata (sender, subject, preview). Use the email ID to fetch the full email content via the API.
How are webhooks secured?
Every webhook delivery is signed with HMAC-SHA256 using your webhook secret. Verify the signature header before processing. Webhook secrets can be rotated at any time from the dashboard.
What is the retry policy for failed deliveries?
Failed webhook deliveries are retried with exponential backoff. After 10 consecutive failures, the webhook is automatically disabled. Rotating the secret resets the failure counter and re-enables the webhook.
Are webhooks HTTPS-only?
Yes. Webhook endpoint URLs must use HTTPS. HTTP endpoints are rejected at creation time.
Rate Limits
What are the rate limits?
API requests are rate-limited per user: 4 requests per second for free users, 10 requests per second for Pro users. Additionally, all users have a monthly operations quota — 1,000 for free users and 100,000 for Pro users.
What happens when I exceed rate limits?
You receive HTTP 429 Too Many Requests. Check the response for details and wait before retrying.
Security & Privacy
How does Mail.td protect my data?
All connections use TLS encryption. Passwords and API tokens are stored as encrypted hashes. Webhook secrets are protected with industry-standard encryption. Mail.td does not use tracking cookies, third-party analytics, or advertising services.
How long is my data retained?
Emails: retained for 7 days by default; after expiration, all emails, attachments, and raw .eml files are permanently deleted.
Mailbox accounts: deleted after 3 months without login.
Pro members: unaffected while subscribed; after downgrade, if not resubscribed within 90 days, all mailboxes under the account are permanently deleted.
Others: revoked API tokens are cleaned up after a retention period; webhook delivery logs are purged after 7 days.
Can other users see my emails or domains?
No. Mailboxes and custom domains are private. Only authenticated users can access their own data.
Troubleshooting
I'm not receiving emails. What should I check?
1. Make sure the sender is using the exact email address shown in your inbox
2. For custom domains, verify that DNS records are correctly configured and the domain status is "verified"
3. Some email providers may delay delivery by a few seconds to minutes
4. Check if the email exceeds the 15 MB size limit — oversized emails are rejected at the SMTP level
5. The sender's IP may be temporarily rate-limited if too many emails were sent in a short period
My custom domain verification failed. What should I do?
1. Check that the TXT verification record is correctly configured
2. Check that the MX record points to the correct SMTP server
3. Allow time for DNS propagation (up to 48 hours)
4. Delete the domain and re-add it to get a new verification token
My webhook shows "failing" status. How do I fix it?
1. Ensure your endpoint returns a 2xx status code within the timeout period
2. Confirm your URL uses HTTPS
3. Ensure your endpoint is publicly accessible
4. Review delivery logs in Dashboard > Webhooks
5. Rotate the webhook secret to reset the failure counter
Still need help?