but when I open waue_contact-led-warehouse-confirm_1.php I can see no mention of the To address, sales@ledwarehouseuk.com. 
the too address is not set in the waue_contact-led-warehouse-confirm_1.php file. it is set on the page that the UE behavior is applied to.
If I remove the dynamic reply address altogether then the forms sends so I'm really not convinced that this is a server issue. 
Well, actually, that does point to the server as the issue.
What that says to me is:
the SMTP server is not relaying emails where the replay and from addresses aren't the same for some reason.


