I am hoping to be able to automatically update a field in my contacts that have a value in Accounts.

Here is the Scenerio...

Parent Account is "XYZ Company", The child companies have contacts with email addresses.   I want to be able to flag all of the child company contacts with "Email Opt Out".

Basically, the Parent company is the only one that I want to email to.   I never want to email the child companies.

Any ideas?