Online
Bento
View markdown

SMTP

Use Bento's SMTP endpoint when your app, framework, or plugin can send email through SMTP but does not support Bento's HTTP Emails API directly.

SMTP submissions are accepted on port 587, upgraded with STARTTLS, parsed, and queued through Bento's transactional email pipeline.

For new server-side integrations, prefer the Emails API. SMTP is best for existing tools that expect a mail server.

Connection Settings

Configure your SMTP client with:

  • Name
    Host
    Description

    yubin.sentbybento.com

  • Name
    Port
    Description

    587

  • Name
    Encryption
    Description

    STARTTLS

  • Name
    Authentication
    Description

    PLAIN

Do not use unencrypted SMTP. Bento requires STARTTLS before authentication, so clients configured without encryption will not be able to sign in.

Credentials

Use your Bento site UUID as the SMTP username. Use your Bento publishable key and secret key joined with a colon as the SMTP password.

Code
Username: your-site-uuid
Password: your_publishable_key:your_secret_key

Example:

Code
Username: a1b2c3d4-e5f6-7890-abcd-ef1234567890
Password: bento_publishable_key:bento_secret_key

The SMTP gateway uses:

  • Username as the Bento site_uuid
  • Password as HTTP Basic auth credentials for Bento, split as publishable_key:secret_key
Treat SMTP credentials like API credentials. Do not paste them into client-side code, public repositories, logs, support screenshots, or browser-exposed configuration.

Message Mapping

Bento converts the SMTP message into a transactional email request.

  • Name
    MAIL FROM
    Description

    Used as the sender when provided. The sender must be an author in your Bento account.

  • Name
    RCPT TO
    Description

    Each recipient becomes one queued Bento email.

  • Name
    Subject
    Description

    Sent as the Bento email subject.

  • Name
    HTML body
    Description

    Sent as html_body when the SMTP message includes HTML.

  • Name
    Text body
    Description

    Used as a fallback when no HTML part exists. Bento escapes the text and preserves line breaks in an HTML wrapper.

  • Name
    Reply-To
    Description

    Sent as the Bento email reply_to value.

If a message contains both text/plain and text/html, Bento uses the HTML part.

Optional Headers

Add these headers to control Bento-specific behavior:

  • Name
    X-Bento-Transactional
    Description

    Set to true, 1, or yes to mark the email as transactional. Transactional emails may be sent even if the recipient has unsubscribed. Use with care.

  • Name
    X-Bento-Layout-Id
    Description

    Applies a Bento layout to the email.

Limitations

  • Attachments are not supported. Link to files instead.
  • The maximum message size is 10 MB.
  • A single SMTP message can include up to 50 recipients.
  • The downstream transactional email queue is still subject to Bento's email API rate limits.
  • The From address must be an author in your Bento account.
Avoid emojis, URL shorteners, and user-controlled personalization in transactional email content. These can hurt deliverability or let users inject unsafe content.

Testing

You can verify STARTTLS from a terminal:

Code
openssl s_client -starttls smtp \
  -connect yubin.sentbybento.com:587 \
  -servername yubin.sentbybento.com

A valid setup should show a certificate for yubin.sentbybento.com and a successful verification result.

To test a real send, configure your SMTP client with the connection settings above and send a message to an address you control.