This article is intentionally direct: standard Proton Mail is not a straightforward fit for 0rd’s IMAP archive sync.
Why Proton is different
0rd Mail Archive syncs from Ordinal’s servers in the EU. The product asks for a reachable IMAP host, port, username, and password (Archive → Connect IMAP archive), then connects outbound over SSL (typically port 993).
Proton Mail does not expose a normal public IMAP server for remote clients the way Gmail or Fastmail do.
Proton Mail Bridge (available on paid Proton plans such as Mail Plus / higher) runs on your computer and offers IMAP only on localhost (your machine). Apps on the same PC can use Bridge; 0rd’s archive workers cannot reach your laptop’s localhost.
So:
| Approach | Works with 0rd Archive sync? |
|---|---|
| Free Proton Mail + remote IMAP | No — no public IMAP endpoint |
| Proton Bridge on your PC | No — Bridge is local-only; 0rd sync is server-side |
| Invented “Sign in with Proton” in 0rd | No — not offered in the product |
Do not try to expose Bridge to the internet (port forwarding / public reverse proxy). That weakens Proton’s model and is not a supported 0rd setup.
What you can do instead
- Import into 0rd (when you already have files)
The Archive UI supports Import ZIP for bringing messages into the archive (separate from live IMAP sync). If you export mail from Proton (or another client) as .eml / ZIP in a form 0rd accepts, you can add historical mail that way. Exact export steps depend on Proton’s current export tools and your plan.
- Archive a different address
If you also use Gmail, Microsoft, iCloud, Fastmail, Yahoo, or any host that offers standard remote IMAP, connect that mailbox with the matching tutorial.
- Ask Ordinal about roadmap
If you need live Proton sync, contact support via your 0rd Account (or contact@ordinal.nl) — there is no documented remote-IMAP path for Proton in the current product.
Plan limits (Proton side)
- Bridge requires a paid Proton Mail plan that includes Bridge. Free Proton Mail does not give you Bridge.
- Even with Bridge, the limitation above still applies: Bridge does not make Proton reachable to 0rd’s servers.
Summary
Proton Mail’s security design (no classic remote IMAP; Bridge stays local) conflicts with how 0rd currently syncs (server-side IMAP). Prefer Import ZIP for one-off history, or connect another IMAP-capable mailbox for ongoing archive sync.
See also: Connect your mailbox overview · All provider guides.