```html
<form action="#" method="post" aria-label="Contact Form">
<div>
<label for="name">Name:</label>
<input type="text" id="name" name="name" required aria-required="true">
</div>
<div>
<label for="email">Email:</label>
<input type="email" id="email" name="email" required aria-required="true">
</div>
<div>
<label for="message">Message:</label>
<textarea id="message" name="message" rows="5" required aria-required="true"></textarea>
</div>
<div>
<button type="submit">Submit</button>
</div>
</form>
```
This HTML code creates a basic contact form with proper accessibility features. Here are some additional notes:
1. The `aria-label` on the form provides a description for screen readers.
2. Each input field has an associated label, which is linked using the `for` attribute.
3. The `required` attribute ensures that all fields must be filled before submission.
4. The `aria-required="true"` attribute informs screen readers that the fields are mandatory.
5. The email input uses `type="email"` for built-in email validation.
To enhance the form's appearance and functionality, you may want to add some CSS for styling and JavaScript for client-side validation and form submission handling.