A common situation where contact form won’t send email may occur depending on server settings.
As you know, WordPress is a PHP based CMS and all features require particular functions to realize. In some cases the PHP mail() function might be disabled from your provider to stop spam exploitation. Usual malware penetrations include spam mail and can cause a great exhaustion of resources even on the most modern applications. Some providers may choose to block the function to prevent spam mail, especially in shared hosting plans.
Some users have reported that even if the mail is sent from the contact form, any given attachment won’t go. This is typically a result of non valid configuration of the form. You need to enter the appropriate tag in the specific field on mail settings, or else the attachment will not be included.
Contact Form 7 is you friend. Please, visit author’s website for more information about using and troubleshooting this great tool.