Mailer Error: Could Not Instantiate Mail Function

Error - Message could not be sent.
Mailer Error: Could not instantiate mail function.
Have Dedicated server
No issue in 2.1.4 PROFESSIONAL
Upgraded to 4.8.1
Order email being sent
This issue only on contact us page. Server guys have done everything (checking ports, php) but no luck.
Anyone can give a direction?

Website->Pages->Contact us->Form builder->Email to:

Website->Pages->Contact us->Form builder->Email to:

Already checked and has email address

This would be a configuration issue. My guess is your SMTP settings in your cart are not correct. Make sure you either remove the var/cache directory or rename it after you make settings changes. My guess is that given you have a dedicated server, you have permission issues which are preventing the cache from being cleared from the cs-cart application (I.e. using ?cc in the admin URL). Note in V2 you could clear the cache from customer or admin. In V4 it's only admin.

Thanks to all for help with input. Issue was with individual email setting on the server.