feat: add is_plaintext support for messages send and drafts create endpoints

CHANGELOG.md

@@ -5,6 +5,7 @@ Unreleased
 ----------
 * Added Yahoo, Zoom, EWS as providers to models/auth.py
 * Fixed grants.update() not using the correct "PATCH" method
+* Added support for `is_plaintext` property in messages send and drafts create endpoints
 
 v6.11.1
 ----------

examples/is_plaintext_demo/README.md

@@ -0,0 +1,156 @@
+# is_plaintext Demo
+
+This example demonstrates the usage of the new `is_plaintext` property for messages and drafts in the Nylas API. This property controls whether message content is sent as plain text or HTML in the MIME data.
+
+## Features Demonstrated
+
+1. **Plain Text Messages**: Shows how to send messages with `is_plaintext=True` to send content as plain text without HTML in MIME data.
+2. **HTML Messages**: Demonstrates sending messages with `is_plaintext=False` to include HTML formatting in MIME data.
+3. **Backwards Compatibility**: Shows that existing code continues to work without specifying the `is_plaintext` property.
+4. **Draft Operations**: Demonstrates using `is_plaintext` with draft creation and updates.
+
+## API Property Overview
+
+### is_plaintext
+
+- **Type**: `boolean`
+- **Default**: `false`
+- **Available in**: 
+  - `messages.send()` - Send message endpoint
+  - `drafts.create()` - Create draft endpoint
+  - `drafts.update()` - Update draft endpoint
+
+When `is_plaintext` is:
+- `true`: The message body is sent as plain text and the MIME data doesn't include the HTML version of the message
+- `false`: The message body is sent as HTML and MIME data includes HTML formatting
+- Not specified: Uses API default behavior (same as `false`)
+
+## Setup
+
+1. Install the SDK in development mode from the repository root:
+```bash
+cd /path/to/nylas-python
+pip install -e .
+```
+
+2. Set your environment variables:
+```bash
+export NYLAS_API_KEY="your_api_key"
+export NYLAS_GRANT_ID="your_grant_id"
+```
+
+3. Run the example from the repository root:
+```bash
+python examples/is_plaintext_demo/is_plaintext_example.py
+```
+
+## Example Output
+
+```
+Demonstrating is_plaintext Property Usage
+=======================================
+
+=== Sending Plain Text Message ===
+Sending message with is_plaintext=True...
+✓ Message request prepared with is_plaintext=True
+📧 Message configured to be sent as plain text (MIME without HTML version)
+
+=== Sending HTML Message ===
+Sending message with is_plaintext=False (HTML)...
+✓ Message request prepared with is_plaintext=False
+🌐 Message configured to be sent as HTML (MIME includes HTML version)
+
+=== Backwards Compatibility (No is_plaintext specified) ===
+Sending message without is_plaintext property...
+✓ Existing code continues to work without modification
+
+=== Creating Plain Text Draft ===
+Creating draft with is_plaintext=True...
+✓ Draft request prepared with is_plaintext=True
+📝 Draft configured to be sent as plain text when sent
+
+Example completed successfully!
+```
+
+## Use Cases
+
+### Plain Text (is_plaintext=true)
+- **Simple Notifications**: System alerts, password resets, account confirmations
+- **Text-Only Emails**: Newsletters or announcements that don't need formatting
+- **Lightweight Messaging**: Reduce message size and improve compatibility
+- **Accessibility**: Better support for screen readers and text-only email clients
+
+### HTML (is_plaintext=false)
+- **Marketing Emails**: Rich formatting, images, and branded content
+- **Newsletters**: Complex layouts with multiple sections and styling
+- **Transactional Emails**: Formatted receipts, invoices, and reports
+- **Interactive Content**: Buttons, links, and styled call-to-action elements
+
+## Code Examples
+
+### Send Plain Text Message
+```python
+message_request = {
+    "to": [{"email": "user@example.com", "name": "User"}],
+    "subject": "Plain Text Notification",
+    "body": "This is a plain text message.",
+    "is_plaintext": True
+}
+
+response = client.messages.send(
+    identifier=grant_id, 
+    request_body=message_request
+)
+```
+
+### Send HTML Message
+```python
+message_request = {
+    "to": [{"email": "user@example.com", "name": "User"}],
+    "subject": "HTML Newsletter",
+    "body": "<h1>Welcome!</h1><p>This is <strong>HTML</strong> content.</p>",
+    "is_plaintext": False
+}
+
+response = client.messages.send(
+    identifier=grant_id, 
+    request_body=message_request
+)
+```
+
+### Create Plain Text Draft
+```python
+draft_request = {
+    "to": [{"email": "user@example.com", "name": "User"}],
+    "subject": "Draft Message",
+    "body": "This draft will be sent as plain text.",
+    "is_plaintext": True
+}
+
+response = client.drafts.create(
+    identifier=grant_id, 
+    request_body=draft_request
+)
+```
+
+## Important Notes
+
+- **Backwards Compatibility**: Existing code without `is_plaintext` continues to work unchanged
+- **Default Behavior**: When `is_plaintext` is not specified, it defaults to `false` (HTML)
+- **Content Type**: The property affects MIME structure, not just content rendering
+- **Safety**: The example includes commented API calls to prevent unintended message sends
+
+## Error Handling
+
+The example includes proper error handling for:
+- Missing environment variables
+- API authentication errors
+- Invalid request parameters
+- Network connectivity issues
+
+## Documentation
+
+For more information about the Nylas Python SDK and message properties, visit:
+- [Nylas Python SDK Documentation](https://developer.nylas.com/docs/sdks/python/)
+- [Nylas API Messages Reference](https://developer.nylas.com/docs/api/v3/ecc/#tag--Messages)
+- [Nylas API Drafts Reference](https://developer.nylas.com/docs/api/v3/ecc/#tag--Drafts)