You could have a table that identifies all the Contacts for a specific Contract.
Contract-->Contact
You would use the ContractID to identify all of the Contacts who should be emailed.
And for each Contact, loop through your "Send an Email" routine.
This suggests that your table and relationships dos not currently support this fact.
It is fundamental to database to ensure your design supports your business before
getting too far into programming, forms, etc.
Good luck.