Retool

Retool can use your own SMTP server for its emails and for the Email resource in apps and workflows. Reference: Send with SMTP.

#Before you start

1. Verify the domain you will send from.
2. Create a sending_access API key for it.

#As a resource (apps and workflows)

Create a new resource of type SMTP (named Email or SMTP in the resource list) with these values:

Then add a query on that resource, fill in recipient, subject and body, and run it. Set the sender explicitly if the resource form asks for one.

#For Retool's own emails (self-hosted)

Self-hosted Retool sends invitations and password resets over SMTP, configured with environment variables on the Retool containers. Check Retool's current documentation for the variable names; point them at the same host, port, username and key as above.

#Alternative: the REST API

Retool's REST API resource is a good fit if you want the email id back or need scheduling, tags or templates, which SMTP does not carry:

• Base URL: https://api.usend.et
• Header: Authorization: Bearer {{ secrets.USEND_API_KEY }}
• Query: POST /emails with a JSON body { "from": "...", "to": ["{{ textInput.value }}"], "subject": "...", "html": "..." }

See Send emails.

#Tips

• Keep the key in Retool's secrets, not in a query.
• A 554 means usend refused the message (for example the sender is not on a verified domain). A 421 means you hit 10 messages per second. See SMTP errors.
• Internal tools often email people on your own team. In the sandbox that works only for verified members of your usend organization.