You can write a script that will send mail, Find the clients you want to mail, specify the To, CC or Bcc fields to use the email addresses in the found set, specify the subject and body of the email and even attach a file.
1 - You can set a script that collects the information you wanna send and that Loop the client table and send each one a seperate mail,
2 - you could Loop the client table and with a variable $Mail = $Mail&";"&Client(Client_Mail)
in this case the variable $Mail will have the same format as To fields with the format mail1;mail2;mail3;......
and collect the information and send the mail.
So, suggestion 1 send a mail to every client and suggestion 2 send all clients one mail.
An additional warning - I've found that some email clients like the comma separating email address and some like semicolons. I've had to do a platform check and have it substitute accordingly since we have a mixed network here.
i believe filemaker uses its own mail client to send emails, so the comma seperated emails will be the appropriate to use.