feat: add HTML email body and attachment support (#20)

CHANGELOG.md

@@ -1,5 +1,20 @@
 # Changelog
 
+## [Unreleased]
+
+### Added
+
+- **HTML email body**: `--html-body` (inline) and `--html-file` (from file) flags on send, reply, and forward. JMAP assembles multipart/alternative automatically when both text and HTML are provided.
+- **File attachments**: `--attachment` / `-a` flag (repeatable) on send, reply, and forward. Files are uploaded as blobs and attached via JMAP's `bodyStructure` with proper multipart/mixed MIME tree.
+- **`upload_blob` JMAP method**: POST raw bytes to Fastmail's upload endpoint, returns a `blobId` for use in email composition.
+- **GraphQL `html_body` parameter**: `sendEmail`, `replyToEmail`, and `forwardEmail` mutations accept optional HTML body content. Previews indicate when HTML is included.
+
+### Changed
+
+- **Refactored body construction**: `create_and_submit_email` now handles plain text, text+HTML (multipart/alternative), and attachments (multipart/mixed with nested alternative) in a single code path. Eliminated duplicated body/cc/bcc logic across compose methods.
+- `bodyValues` keys changed from `"body"` to `"textBody"` / `"htmlBody"` for clarity.
+- `mime_from_filename` in util.rs is now public (used by `load_attachment`).
+
 ## [2.0.1] - 2026-03-26
 
 ### Fixed

Cargo.toml

@@ -47,6 +47,10 @@ tracing = "0.1.44"
 tracing-subscriber = { version = "0.3.22", features = ["env-filter"] }
 roxmltree = "0.21.1"
 
+[dev-dependencies]
+tempfile = "3"
+wiremock = "0.6"
+
 [profile.release]
 strip = true
 lto = true

README.md

@@ -6,7 +6,7 @@ CLI for Fastmail's JMAP API. Read, search, send, and manage emails from your ter
 
 | Feature               | Description                                                            |
 | --------------------- | ---------------------------------------------------------------------- |
-| **Email**             | List, search, read, send, reply, forward, threads, identity selection  |
+| **Email**             | List, search, read, send, reply, forward, threads, identity selection, HTML bodies, file attachments |
 | **Mailboxes**         | List folders, move emails, mark spam/read                              |
 | **Contacts**          | Search contacts via CardDAV                                            |
 | **Attachments**       | Download files, extract text, resize images                            |
@@ -158,6 +158,26 @@ fastmail-cli send \
   --from "alias@yourdomain.com" \
   --subject "Hello" \
   --body "Message"
+
+# HTML email body (inline or from file)
+fastmail-cli send \
+  --to "alice@example.com" \
+  --subject "Newsletter" \
+  --body "Plain text fallback" \
+  --html-body "<h1>Hello</h1><p>Rich content here</p>"
+
+fastmail-cli send \
+  --to "alice@example.com" \
+  --subject "Report" \
+  --body "See attached" \
+  --html-file ./email.html
+
+# File attachments (repeatable)
+fastmail-cli send \
+  --to "alice@example.com" \
+  --subject "Documents" \
+  --body "Please review" \
+  -a report.pdf -a data.xlsx
 ```
 
 ### Move Email