You must correctly serve (ie deliver) your all Party Wall Notice. To serve a Party Wall Notice, the property owner must either:
deliver it to the recipient (ie the relevant adjoining owner) in person
send it by post to the recipient’s usual or last-known residential address or place of business in the UK, or
if the recipient is a body corporate (eg a company), deliver it to the secretary or clerk at the registered or principal office
Party Wall Notices may alternatively be served to an email address specified by the recipient, but only if the recipient has previously stated that they are willing to receive such notices by electronic communication and this statement has not been withdrawn.
If you do not know the adjoining owner’s name, you can address your Party Wall Notice to ‘the owner’. You must then serve it either by delivering it to a person at the property by hand or, if nobody appropriate can be found at the property, by affixing it to an obvious part of the property.