If you are getting error message while sending email from contact form ( template or VC addon) please follow this steps:
Please install Check mail plugin https://wordpress.org/plugins/check-email/ for wordpress
Then navigate in Wp Dashboard > Tools > Check email and enter your email as shown on image below
and hit test button, if you will not receive test email it means that you hosting php mail send function have issues and please contact hosting provider to help you with this.
If they are unable to solve this issue you can use contact form 7 plugin https://wordpress.org/plugins/contact-form-7/ (it’s fully supported) , this plugin does not require php mail function and works on most hostings.
If you will receive test Email then contact us and provide site URL/Username/Password and i will login and check it.
thats Is 🙂