Filtering incoming mails with sender-domain = recipient-domain?

[Jannis Kafkoulas]

Hi,

Sometimes we receive mails with sender-domain our company,
i.e. from: any...@mycompany.com to: some...@mycompany.com which we'd like to 
block (the entire domain).
Can it be done e.g. by header checks?
Or is it possible at all?

Thanks

jannis