the session contenst are showing the form address and to address as:
Enquirey@ Stag'n'Hen Do T shirts Reply-To: Enquirey@ Stag'n'Hen Do T shirts
there are 2 problems with this:
1) neither of these are a valid email address. a valid email address must have a TLD at the end, for example .com or .org. a valid email address can contain only letters and numbers. the only exceptions are the dot and underscore characters you have spaces and single quotes in the address which is not valid.
2) you are using the same address for the from and to address. most SMTP servers will not accept an email that uses the same address for the from and to address, it will be treated as spam.