need to sent mail from server very slowly .
I have installed postfix server in ubuntu , thats is working fine , but i need to sent mail from server very slowly ,
Because some time we will sent bulk mails , so all mails send together so receiver will consider as a spam,
So i need to send mail very slowly , one minute maximum sent 33 mails , same time all mails should be in queue .
Can you advice me how to do that