I am testing it and it seems to run every 5 minutes to sync. Handles standard IMAP and POP inboxes. No auth for main page, so they caution appropriately to avoid public facing web exposure. They are planning on adding more support for Gmail and the like:

https://github.com/bandundu/email-archiver/issues/6

It installs by default in debug mode which may or may not be a red flag depending on your security model.

The email search is fast, but could use work, I will say it is VERY early in development. But for downloading email for later storage, it should do. It stores your e-mails in a SQLite database in the same directory as the installer, so if you want to manipulate the compose file a bit, it should be able to point to your desired storage directory. With that said, I also was able to add a TZ= directive so my logs at least are a bit cleaner with timestamps to match my timezone, something they have not added.

If you wish to access this remotely before they add a public facing login, protect it with a SSO solution or other front facing login setup so it would not be accessible. Or securely access it via Wireguard, TailScale, or Headscale.