Your AI wrote your app's email.
Have you read it?

Move this app’s outgoing email onto Mailway. Mailway sits in front of the email provider the app already uses: it sends every mail through my own provider account and keeps an exact copy of it. Read mailway.net/llms.txt before you start.

I want three things from this change: to read every mail the app sends, to test mail without it reaching a customer, and to keep the provider I already have.

1. List every mail first, then stop. Find every place in this codebase that sends email, and every mail another service sends for the app, such as Supabase Auth. Show them as a table: the mail, what triggers it, who receives it, its template or text, and how it’s sent today (SMTP, an SDK, an HTTP API, or another service). Under the table, point out anything that looks wrong: a link built from localhost or a development URL, a template value that can be empty, code that can send the same mail twice (on a retry, a page reload, or a double click), and test text or test addresses. If you see a reason this move won’t work for this app, say so there. Then stop, and change nothing until I tell you to go on.
2. SMTP. If the app sends over SMTP, change only the connection settings: the host from MAILWAY_SMTP_HOST, port 587 with STARTTLS, and the username and password from MAILWAY_SMTP_USERNAME and MAILWAY_SMTP_PASSWORD. If port 587 is blocked or hangs where the app runs, use 2525, also with STARTTLS.
3. A provider’s SDK or HTTP API, for example the Resend SDK. Replace those calls with Mailway’s send endpoint, POST {MAILWAY_API_URL}/v1/send, with the key from MAILWAY_API_KEY. Keep every field of each mail: from, to, cc, bcc, reply_to, subject, html, text, attachments, and headers. Write a from with a display name as {"email": …, "name": …}, because Mailway doesn’t accept the "Name <address>" string. Send an Idempotency-Key header of 12–40 characters (letters, digits, - and _). Build it from something unique to this one mail, such as the order ID or the reset request’s ID, so a retry of the same mail repeats the key. Never reuse a key for a later mail: Mailway keeps every key for the life of the project and answers a repeat without sending.
4. The sandbox for development and preview builds. Production uses smtp.mailway.net, or https://api.mailway.net with a live key (mw_live_…). Development and preview builds use smtp.mailway.dev with the same SMTP credential, or https://api.mailway.dev with a test key (mw_test_…). Mailway keeps sandbox mail and sends none of it to a provider unless someone releases it in the console.
5. Mail another service sends. Don’t change code for it. If the service lets me set custom SMTP, as Supabase Auth does, tell me where to turn it on and list the values to enter.

When you’re done, tell me:

• which environment variables to set, with the production value and the development and preview value of each;
• which mail from the list to trigger first in a preview build, so I can read it in the Mailway console under Mails;
• which settings of the old provider the app no longer uses. Don’t remove them until I confirm that a real mail sent through Mailway reached my inbox.

Rules. Adapt the change to the existing code. Don’t add a standalone example. Never put a secret in the code or in a committed file, and never ask me to paste one into this chat.