So what would be the solution? Because the current acs email service method is flawed if it sends mails one-by-one to the recipient by copying cc and bcc. 

unfortunately, this methodemailService.sendEmail("/etc/notification/email/email-template.txt",emailParams,attachments,toEmails,ccEmails,bccEmails);doesn't even exist

I'm using ACS commons to send mail like this. the EmailService is from ACS commons. Problem here is the service sends the mail to each recepient in toEmail separately while also having ccemail and bccrecpient in it. This causes mail to be tiggered to the ccemail and bccrecepient multiple times which...