Email Archiving POP3 Access

We host some local city/village/county government web and mail. They are required by FOIA to retain all sent and received emails. Obviously 10 years of email storage is not something I want to be responsible for, and they all agree.

I have an old Exim hack that sends all incoming and outgoing messages for each required domain into archive@domain.tld. They pick up the messages every 5 minutes or so via POP3 and they are gone from my system, just the way I like it.

I would like to make use of the new(ish) Email Archiving built into cPanel. However, it is only accessible via read-only IMAP. This obviously imposes issues with the way things are happening now. If I enabled the cPanel-provided archiving functionality, they will not be able to retain the messages permanently at their desired location due to IMAP being server-side obviously.

I'd like to propose allowing read-only POP3 access to the _archive accounts so that we can give them a 30-day window to pick up the messages. I suppose the only issue here would be that the POP3 access is also read-only and when the POP3 client attempts to remove read messages from the server, it will most likely encounter an error. But does that really matter? Probably not. As long as they download the messages, they will go away on the server at the end of the archive period.

I could be totally wrong here. Feel free to tell me I'm stupid.