Not Receiving Contact Emails

Hi,

We are running WP 4.0.8 and using Ninja Forms in conjunction with the Flatsome Theme v2.0.1. It seems are emails are not sending consistently via the Contact Form actions?

Can you please look into this asap or tell us if you are having other related issues for clients?

Our web site is here:
http://paris-france-tours.com/

We have Ninja Forms Version 2.9.28
Thanks,
TK

https://ww.wp.xz.cn/plugins/ninja-forms/