Question about sendmail access format

[khuul]

Hi,

I need help on how to put in the access file to allow email from some relay and reject others.

For example, I want to allow any email with the sender's domain of "business.com" coming from mail relay of "a.business.com". But reject any email with the sender's domain "business.com" from other mail relays such as "bellsouth.net" or "comcast.net".

How can I put in the access file for this?

Thanks