Modal Contact Form (modal-contact-form) free WordPress plugin

Modal Contact Form is a plugin which allows to insert a shortcode where you want to provide a contact button on your site.
Clicking on this button then opens a modal contact form with following features:

• Slider captcha validation (Send button is visible only after drag the slider).
• Modal window is CSS only
• Form fields are: Name, Email (optional), Phone number(optional), Message, Checkbox to receive a copy (if Email option is enabled)
• Optional field is file attachment (extensions allowed are jpg, jpeg, jpe, pdf, zip, png, txt, doc, docx, xls, xlsx, xla, xlt and xlw). Chosen rule : In case attached file extension is not allowed, mail is still sent but without file attached
• Autoreply feature to add a specific message to your copy message when you are out of office
• Languages translation ready for frontend and backend (English/French provided)
• One default style CSS provided (lb-modal-contact-form.css) which can be turned off in admin interface to use your own

Note that it is also possible to disable modal window and just have contact form inside a page or post.