How to filter email using regex or other technique?

My email server is attacked by suspicious email and I want to filter it. The email body has a familiar email name in the form of hyperlink. It also use a familiar email subject. I'd like to filter this email. Perhaps, using a regex that detect a single word text and contain "@ash.com". It is even better if I can combine the filter as if it's a hyperlink. I'll attach some images about th email virus. I'm new about filtering emails. So, any help is greatly appreciated