Archive from any IMAP account.
Exchange is supported for Apple Mail, and Microsoft Entourage and Outlook.
You can archive Gmail via your mail client or directly.
Mail Archiver X can archive mbox files without any mail client.
The built-in browser has the familar 3-pane interface of every mail client.
You can archive directly to the Internal Database, Filemaker - if you have a Filemaker license -, PDF and Evernote. If you archive to the internal database you can export the complete or partial data to Evernote, Filemaker, PDF, MBOX or Text (csv).
Each format has options to tailor the export to your needs. The screenshot shows the options for PDF.
If you have a Filemaker license then you can use Filemaker for your archive. Filemaker versions 16-18 are supported.
It's just a bit annoying to remember to do something. Archive daily, weekly, monthly or once a quarter.
Any questions that this page didn't solve? Go to Moth Software support and ask.