---
title: "File, MailKaro Docs"
description: "Share any file from an email or a page: a PDF, a text file, a CSV, an XML feed, an HTML page, a Word, Excel or PowerPoint file, a ZIP."
---

# File

Content blocks

# File

Share any file from an email or a page: a PDF, a text file, a CSV, an XML feed, an HTML page, a Word, Excel or PowerPoint file, a ZIP. Users upload it in the block, and a Preview switch can show the file right in the editor.

## What the reader gets

The exported email holds a **download card**: the file's type badge, its name and size, and a button with your link. Email apps cannot show a PDF or run a page, so the file itself is never put in the email. Preview only changes what *you* see while building.

## Preview

Turn on **Show preview in the editor** in the block's Preview section. The file then appears on the canvas and in Preview mode; the height is yours to set (200 to 900 px).

|Kind |Extensions |What you see |
|PDF |`pdf` |The browser's PDF viewer, scrollable page by page |
|CSV / TSV |`csv, tsv` |A table with a sticky header and row numbers. Scroll to read every row: more rows load as you scroll, so a file of any size stays smooth |
|XML |`xml` |Indented, each element on its own line, scrollable to the end |
|HTML |`html, htm` |Rendered as a page, in a sandbox that runs no scripts |
|Text and JSON |`txt, md, log, json` |As text (JSON is indented), scrollable to the end |
|Media |`png, jpg, gif, webp, mp4, webm, mp3, wav` |An image, a video or an audio player |
|Others |`doc, docx, xls, xlsx, ppt, pptx, zip` |No preview. They still download from the email |

ℹ The preview reads the file in the browser, so the host of the file must allow it (CORS). A file served from your own bucket through `uploadFile` below does. If a file cannot be read, the block says so and links to the file. Files over 10 MB show their first 10 MB, and say so.

## Uploading

The block takes any file through your [upload handler](https://mailkaro.com/docs/image-uploads), the same` assets.onImageUpload` that images use, called with `kind: "file"`. Without a handler the editor refuses a file upload (a base64 file would bloat the email). The editor also checks the file against the [email size limit](https://mailkaro.com/docs/image-uploads) when you set one.

ts server.ts

```
// your backend route: POST /upload (multipart field "file")
const stored = await admin.uploadFile({
 buffer: file.buffer, filename: file.originalname, contentType: file.mimetype, scopeId: req.user.orgId
});
// -> { url, contentType, name, size } (the editor puts these in the block)
```

`admin.uploadFile` in `email-craft-sdk` is built for this. Per-tenant key prefix (`scopeId` is required), 20 MB cap, and the type is judged from the file's bytes, never from what the browser claims. It accepts PDF, text, CSV, JSON, XML, HTML, RTF, Word, Excel, PowerPoint, ODT, ODS, ZIP and PNG, JPEG, GIF, WebP, AVIF images, and refuses scripts, programs and SVG (use `uploadAsset` for SVG, which cleans it).

⚠ Pages and feeds (HTML, XML) are stored as plain text and as a download, so opened from your bucket they never run as a page on that origin. Previews of them are rendered by the editor, inside the sandbox above.

## Block values

|Property |Controls |Default |
|`url` |The file's public link (set by the upload) |, |
|`name` |File name shown on the card |(from the link) |
|`mime / size` |Type and size in bytes, set by the upload |, |
|`button_label` |The download button text |Download |
|`preview` |Show the file in the editor (never in the email) |false |
|`preview_height` |Preview height, 200–900 px |420 |
|`background_color / border_color / border_radius / padding` |The card |#ffffff / #d9dce5 / 12 / 16 |
|`button_color / button_text_color` |The download button |#14213d / #ffffff |
|`container_padding` |Space above and below |token.spacing |

The File block is part of the free editor. The MCP server and Cloud API know it as `file` (see `get_block_schema`); the quality check warns when a file block has no file.

Source: https://docs.mailkaro.com/block-file