SMTP (Sending Email)

What this feature is for

SMTP access lets you send email from any standard email client or application using your Inboxlayer inboxes. Messages sent via SMTP are delivered through AWS SES and automatically appear in your Sent folder.

Connection settings

Authentication

SMTP authentication uses API tokens, not account passwords.

1. Sign in to your Inboxlayer account.
2. Go to Account Settings > API Keys.
3. Create a new token or copy an existing one.
4. Use the full token value as your SMTP password.

The username is your inbox email address:

• Default domain: inbox_name@inboxlayer.dev
• Custom domain: inbox_name@yourdomain.com (if domain is verified)

What happens when you send

1. Your client connects and authenticates with the API token.
2. Inboxlayer verifies token ownership and checks your send quota.
3. The message is relayed through AWS SES.
4. A copy is written to your inbox's Sent folder automatically.
5. An OutboundEmail record is created and tracked for delivery status.

Quotas and limits

Send quotas are enforced at the SMTP level, same as the API. If your plan's send limit is reached, the SMTP server will reject the message. Check your plan details for specific limits.

Ports

Use port 587 with STARTTLS for most clients. This is the recommended configuration.

Port 465 (implicit TLS) is also supported. Some ISPs or corporate networks block port 465, so 587 is the safer default.

Port 25 is reserved for inbound mail delivery and cannot be used for sending.

Notes for agents

• API tokens used for SMTP are the same tokens used for API and IMAP access.
• Tokens can be revoked independently without affecting other tokens.
• Track OutboundEmail status via the API if you need delivery confirmation.
• The same rate limits apply whether sending via SMTP or the REST API.