Deleting emails by user's domain in Exchange

Hi,

I am trying to copy all emails in Exchange from a specific a sender's domain to .PST then delete them all.

So far I am only able to copy into a folder and delete by sender's email address and not the sender's domain.

This is what I am using.

get-mailbox | Search-Mailbox -SearchQuery ‘From:name@domain.com ‘ -TargetMailbox “helpdesk” -TargetFolder “Export” -LogLevel Full –DeleteContent 

How do I get to it become *:*@domain.com where it picks all of the domain and not just the single sender?

Or what is a better way of accomplishing this?