Mail merge using Pages and Numbers

Greetings to all. I have searched for my particular type of problem and haven't found it or a solution. If this is a repeat, I apologize. My question is can I do a merge using pages and numbers and make sure that particular documents go to particular people?

The situation is I do a monthly newsletter and send it out to 300+ organizations. I have been able to personalize these using merge (company name) fields in Numbers to the newsletter which is done in Pages. However, I need to find a way to insert in these newsletters an acknowledgement for contributions made by certain organizations each month and have those particular newsletters be sent out using Mail to those particular recipients all within a mass email instead of one by one.

Can anyone give me some advice or a possible solution with or without sticking to Numbers/Pages/Mail.

Your help will be greatly appreciated.

Greg