Amazon SES email template studio with preview and version history

I want an email template studio for Amazon SES so marketing and support ops can change transactional copy without waiting on a deploy. The people using it are not engineers, so keep every screen in plain language and make it hard to break something.

The app opens on a library of every email template in the SES account, loaded with List Email Templates. Show each template by name, let me search the list by name, and open the editor when I pick one.

The editor loads the selected template with Get Email Template and shows three editable fields: the subject line, the HTML part and the text part. Beside the fields sits a live preview pane. Render the preview with Test Render Email Template, passing the current editor contents together with the active sample data. Test Render Email Template returns MIME content, so parse the HTML part out of the MIME and render that inside a sandboxed iframe rather than dumping raw MIME on screen. Re-render shortly after I stop typing instead of on every keystroke.

Sample data is a small set of key and value pairs that fill the personalization variables in the template. I can type the values in directly, or pull them from a Google Sheet of example customers. For the sheet route, let me set the spreadsheet and range once, read it with Get Values, treat the first row as column headers, and list the remaining rows in a picker. Selecting a row fills the sample data from that row, so the preview shows a real name, plan tier and order value instead of placeholder text.

Saving writes the subject, HTML and text back through Update Email Template. SES keeps no version history of its own, so the app has to keep one. On every successful save, store a snapshot in the app's own storage holding the template name, the subject, the HTML part, the text part, the person who saved it, a one line note I type in the save dialog, and the timestamp. A History panel lists the snapshots for the current template newest first. I can open any snapshot to read it, and I can restore one, which loads it back into the editor fields. Restoring does not write to SES by itself. I still press save, which creates a new snapshot recording that it came from an earlier version.

Before every save, scan the subject, HTML and text for personalization variables and compare them against the keys present in the active sample data. If the copy references a variable the sample data does not provide, show a warning that names the missing variables and make me confirm before the save goes through. This matters because a template whose variables are not supplied fails to render, so the check catches a broken email before it ships.

A New template button opens the same editor empty, asks for a template name, and creates it with Create Email Template. Record its first snapshot on creation.

There are two send buttons. Send to me delivers the current preview to my own address using Send Email. Send to reviewers delivers it to a short list of addresses I type in, using Send Bulk Email. Cap the reviewer list at about ten addresses and label it clearly as a review send. This app is a proofing tool, not a campaign blaster, and should never be pointed at a customer list. The From address for both buttons is a dropdown of the account's verified senders loaded with List Email Identities, so I cannot send from an address SES has not verified.

A few guardrails. Always show which template is selected and whether it has unsaved changes. If a save or a send fails, show the reason in plain language near the button that triggered it rather than a raw error. If the account is still in the SES sandbox, sends only reach verified addresses, so say that plainly when a review send is rejected for that reason.