Email archiving for 500 accounts

One of our domains (example.com) has about 500 email accounts. We will like to create an archive of each account where we can store all the incoming and outgoing emails of the account for say, 30 days.

Proposed option:

We can create a new account like account1copy@example.com and forward all the incoming emails for account1@example.com to this.

Questions:

1. Will the Cpanel forward option forward all the emails meant for the account or only the emails that are left after Exim filter and Spamassassin have deleted a few emails?

2. How do we copy all the outgoing emails to this email account? Do we need to create an entry in the exim-filter file for each account. Since there are 500 email accounts, will this slow down the email delivery heavily? Is there a better alternative?

3. How to create a copy account for each of the 500 accounts in bulk?

4. I assume we can run a cron script to delete all emails in the copy accounts only that are more than 30 days old.

We are unable to use the Cpanel archive feature because

a. It stores all the messages that the account receives including spam etc. It archives the emails before the Exim filter and Spamassassin have had a shot at the emails.

b. It stores all the emails in a single email box.

 

I have reviewed that thread.

As I mentioned, archive options won't work for us.

Does it mean, I have to manually add sections to the copy of the Exim filter file for the blind copy of each of the 500 accounts? Is there an alternative way? I am also concerned about maintenance as we might be adding new accounts rather frequently.

 

Thanks for your inputs. Appreciate it.