Migrate to/from Fastmail Files (WebDAV)

What is Fastmail?

Fastmail is the privacy-focused email service that's been operating from Australia since 1999 — one of the oldest independent IMAP-friendly email hosts still standing. Best known for fast IMAP, custom domains, JMAP API, and a clean web interface, Fastmail also includes a file storage feature bundled with paid plans: a per-user files area accessible through the web UI, the WebDAV protocol, and the JMAP API. The files area isn't intended as a standalone cloud-storage replacement (Fastmail's file quotas are smaller than Google Drive's), but it's useful for email attachment storage, document hosting accessible from your Fastmail webmail, and small-team file sharing alongside email-centric workflows.

What makes Fastmail's files area integration uniquely tricky for third-party tools is the app-password authentication: Fastmail doesn't accept your main account password for WebDAV (or for any non-browser API path) — every external tool requires a dedicated app password generated from your Fastmail security settings, with explicit permission scoping. CloudsLinker uses this app-password approach, with the Files (WebDAV) permission scope specifically. Each app password is 16 characters with 80 bits of entropy — extremely difficult to brute-force, and individually revocable from Fastmail's settings without affecting other apps or your main account password. Common use cases: migrating files from Fastmail to a larger primary cloud (Google Drive, OneDrive), or backing up Fastmail files to S3 / Wasabi as part of an email-data archival strategy.

Key features of Fastmail

Australian privacy-focused email

Operating from Australia since 1999. One of the oldest independent email hosts still standing. Includes file storage with paid email plans.

WebDAV access bundled

Files stored in Fastmail are accessible via WebDAV — the standard protocol CloudsLinker uses. Not a primary cloud-storage replacement, but useful for email-attachment-tier file storage.

App passwords required (no main pw)

Fastmail doesn't accept your main account password for WebDAV. App passwords are required — generated from <code>Settings → Privacy & Security → App Passwords</code> with explicit scope (Files (WebDAV)).

16 characters, 80 bits entropy

Fastmail app passwords are 16 characters with 80 bits of entropy — extremely difficult to brute-force. Individually revocable per app without affecting your main account.

Storage tied to email plan

Files quota is included with paid Fastmail plans (Standard, Professional, Topicbox). Free tier has minimal file storage. For dedicated cloud storage, larger plans like Google Drive or OneDrive are more appropriate.

JMAP API for advanced workflows

Fastmail also exposes a JMAP API for programmatic access — modern JSON-based replacement for IMAP. CloudsLinker uses WebDAV for the Files area, not JMAP.

Why connect Fastmail to CloudsLinker

CloudsLinker connects to Fastmail Files via WebDAV using your full Fastmail username (e.g. [email protected]) and a Fastmail app password generated with the Files (WebDAV) permission scope. The connection runs over HTTPS to Fastmail's WebDAV endpoint. Once connected, transfers run server-to-server — pulling files from Fastmail's storage and writing them to the destination cloud over the destination's native API. Use as source for migrating Fastmail files content out, as destination for backing up other clouds into Fastmail (mainly for email-attachment-archival workflows), or for cross-cloud sync.

What you can do with Fastmail on CloudsLinker

Fastmail Files → any cloud copy

Migrate from Fastmail Files to Google Drive, OneDrive, Dropbox, S3, Wasabi or B2 — useful for offloading email-attachment-archive content to a larger primary cloud.

Runs on our servers

Fastmail transfers execute on CloudsLinker infrastructure. Useful for migrating multi-GB Files content without consuming local bandwidth.

Scheduled & incremental sync

Hourly / daily / weekly schedules. Useful for ongoing backup of Fastmail Files content to off-site cloud storage, especially for compliance-heavy email-archival workflows.

Filter by folder, type, size

Migrate only specific Fastmail folders, exclude files larger than the destination's cap, or back up just office documents and PDFs.

Common Fastmail transfer scenarios

Email attachment archive: Fastmail Files → S3 / Wasabi cold storage

Email-archival-conscious users save important attachments to Fastmail Files for organized retrieval. Schedule a CloudsLinker monthly incremental from Fastmail Files to S3 Glacier Instant Retrieval ($0.004/GB) or Wasabi ($6.99/TB) for long-term archival with Object Lock immutability.

Migrate Fastmail Files → Google Drive / Dropbox for larger storage

Fastmail's Files area isn't designed as a primary cloud-storage replacement. If you've outgrown the included quota, migrate Files content to Google Drive (15 GB free, 2 TB at $9.99/mo) or Dropbox while keeping Fastmail for email. CloudsLinker handles the bulk migration via WebDAV.

Cross-cloud DR: Fastmail Files + Proton Mail attachments → unified backup

Privacy-focused users running Fastmail (email + files) and Proton Mail (encrypted email) often want a unified backup of both. CloudsLinker can pull from Fastmail Files via WebDAV and from other clouds via their respective connectors — consolidating into a single S3 / B2 backup destination.

Document hosting: Fastmail Files → public-facing storage migration

Some users host small static documents (PDFs, presentations) on Fastmail Files for sharing via email-style links. Migrate to dedicated static hosting (Cloudflare R2 + Pages, Backblaze B2) for better reliability and CDN performance — CloudsLinker handles the transfer with folder structure preserved.

Cold-archive old Fastmail files before downsizing email plan

If you're downsizing from Fastmail Professional (larger Files quota) to Standard (smaller quota), migrate cold Files content to S3 / B2 first via CloudsLinker. Avoids losing access when the smaller plan kicks in.

How to connect Fastmail to CloudsLinker

Fastmail Files uses WebDAV with app password authentication — the main account password is not accepted.

Before you start

Generate a Fastmail app password with WebDAV permission:

Sign in to https://www.fastmail.com with your normal account credentials.
Click your avatar (top right) → Settings.
Click Privacy & Security in the left sidebar.
Scroll to App Passwords → click + New App Password.
Enter a name for the password (e.g. cloudslinker).
Under Permissions, select Files (WebDAV) — this is the scope CloudsLinker needs. Other scopes (IMAP, JMAP, etc.) can also be selected if you want this password reused for other protocols, but Files (WebDAV) alone is sufficient.
Click Generate. Fastmail displays the 16-character app password once. Copy it immediately.

Connection steps

In CloudsLinker, click Add Cloud → choose Fastmail.
Enter a display name (e.g. “Fastmail Files”).
Enter the WebDAV URL: https://myfiles.fastmail.com/
Enter your username — your full Fastmail email address (e.g. [email protected]).
Enter the app password from step 7 above (NOT your main Fastmail login password).
Click Confirm — CloudsLinker validates with a PROPFIND request and shows the connection ready.

Revoke access

To revoke CloudsLinker’s app password later: https://www.fastmail.com → Settings → Privacy & Security → App Passwords → find the entry → click delete. The app password becomes immediately invalid; your main account password is unaffected.

Fastmail Files upload & download limits you should know

Fastmail’s Files area is bundled with paid email plans, so most “limits” are tied to your email plan tier:

Storage quota: included with paid Fastmail plans (Standard, Professional, etc.); varies by tier — typically a few GB on Standard, more on Professional. Check fastmail.com → Settings → Account → Storage for exact current quota.
WebDAV endpoint: https://myfiles.fastmail.com/.
Authentication: app password only — main account password is rejected for WebDAV.
App password format: 16 characters with 80 bits of entropy (e.g. abcd-efgh-ijkl-mnop).
Per-file size: no published Fastmail-specific cap; bounded by WebDAV / HTTP timeout for very large transfers.
Bandwidth: no separate cap; tied to your Fastmail plan’s overall transfer allowance.
Trash retention: files deleted from Fastmail Files typically retained 30 days before permanent deletion.
Versioning: not a primary feature; for version history, use a destination cloud with versioning (S3, B2, Wasabi, Google Drive).
Service longevity: Fastmail operating since 1999 — 25+ year track record.
Geographic hosting: Australia (primary), with regional points of presence.

Sources: Fastmail: About Fastmail file storage, Fastmail: Remote file access (WebDAV), Fastmail: App passwords, Fastmail: Updated file storage with WebDAV access.

Fastmail + CloudsLinker — Frequently Asked Questions

Is Fastmail Files a real cloud-storage replacement?

No. Fastmail Files is a complementary feature bundled with paid email plans, designed for email-attachment-tier storage and basic document hosting. For primary cloud storage at scale, Google Drive (15 GB free → 30 TB Google One) or OneDrive (5 GB free → 25 TB Enterprise) are the right choices. Fastmail Files is useful when you want files alongside email without managing a separate cloud account.

Why do I need an app password instead of my main Fastmail password?

Fastmail's security model requires app passwords for all non-browser access (WebDAV, IMAP, SMTP, JMAP). Your main account password is for the browser login only. App passwords are scoped per-application (Files / IMAP / Calendar), 16 characters with 80 bits of entropy, and individually revocable. This means a compromised app password doesn't expose your full account.

How do I generate a Fastmail app password?

Sign in to fastmail.com → click your avatar → Settings → Privacy & Security → App Passwords → click + New App Password → enter a name (e.g. 'CloudsLinker') → select Files (WebDAV) permission scope → click Generate. Copy the displayed app password — Fastmail shows it once.

What's the WebDAV URL for Fastmail Files?

Fastmail's WebDAV endpoint is at https://myfiles.fastmail.com/. Use this as the WebDAV URL when connecting CloudsLinker. Username is your full Fastmail email address (e.g. [email protected]); password is the app password from step above.

Are my Fastmail credentials safe with CloudsLinker?

Yes. The username + app password are encrypted at rest with AES-256 and decrypted only inside the active transfer worker. Best practice: use Fastmail's app password mechanism (which CloudsLinker requires) rather than your main account password — the app password is account-scoped and individually revocable.

What's my Fastmail Files storage limit?

Depends on your Fastmail plan tier. The Files quota is bundled with paid plans (Standard, Professional, etc.) and varies — typically a few GB on Standard, more on Professional. For exact current quotas, check fastmail.com → Settings → Account → Storage. Free trial plans have minimal Files allocation.

How fast can CloudsLinker transfer Fastmail Files?

Throughput depends on Fastmail's WebDAV server performance and the destination cloud's ingress speed. Typical sustained throughput is 50–200 GB/day per connection. WebDAV's per-file overhead means many small files transfer slower than fewer large files.

Can I migrate between two Fastmail accounts?

Yes. Connect each Fastmail account as a separate cloud in CloudsLinker (each with its own app password), then run an account-to-account copy. Folder structure and file content transfer; sharing-link metadata doesn't (Fastmail-specific).

Does CloudsLinker support Fastmail's JMAP API?

Not currently — CloudsLinker uses Fastmail's WebDAV endpoint for Files access, which is the standard protocol Fastmail recommends for third-party file-sync tools. JMAP is primarily oriented at email/calendar/contacts, not file storage.

Is this an official Fastmail partnership?

No. CloudsLinker is a third-party tool that uses Fastmail's standard WebDAV endpoint with app-password authentication. Revoke access by deleting the app password from fastmail.com → Settings → Privacy & Security → App Passwords.

Fastmail transfer guides

Step-by-step walkthroughs for moving data to and from Fastmail.

Easy File Transfer from Google Drive to Fastmail

Learn how to effortlessly transfer files from Google Drive to Fastmail in this comprehensive guide.

Conclusion

Fastmail's Files area is a complementary file-storage feature bundled with the email service — not a primary cloud-storage replacement, but useful for email-attachment-archival workflows and document hosting alongside Fastmail's email features. CloudsLinker connects via WebDAV with Fastmail's app-password mechanism, enabling clean migration to / from larger clouds (Google Drive, OneDrive, S3) or off-site backup of Fastmail Files content. Generate an app password with the Files (WebDAV) scope and run your first migration in minutes.

Start Your Free Fastmail Transfer