Mailbox Taxi vs Stellar Converter: Migration vs Conversion

Stellar Converter and Mailbox Taxi often show up in the same shortlist, but they're solving different problems. Stellar is a Windows utility for opening, repairing, and converting mailbox files on disk — PST, OST, MBOX. Mailbox Taxi is a cross-platform desktop app for moving live mail between IMAP servers. If your job is "this PST file is sitting on a USB stick, get the mail out of it," Stellar is the right tool. If your job is "move 60 mailboxes from Gmail to Microsoft 365 by Monday," that's Mailbox Taxi territory. This comparison sorts out which one fits your actual job.

TL;DR#

What each tool actually is#

Stellar's mail-conversion product line — Converter for OST, Converter for PST, Converter for MBOX, and a Toolkit bundle that combines them — is a set of Windows utilities. Each one opens a mailbox file on disk, parses its internal structure, and exports messages to another format (PST to MBOX, OST to PST, MBOX to EML, and so on). The same engines also handle repair, pulling readable mail out of files that Outlook itself refuses to mount. The interface is wizard-driven and familiar to anyone who has used a Stellar product before.

Mailbox Taxi is a desktop app for Windows, macOS and Linux that connects to live IMAP servers and moves messages between them. It speaks OAuth2 to Gmail and Microsoft 365, app passwords or basic auth to everything else, and handles bulk runs from a CSV of mailbox pairs. The data path is source-IMAP → your laptop → destination-IMAP. There is no file format manipulation involved; the mail lives on a server at both ends.

If you're trying to decide which side of the file-vs-server line your job is on, the PST/MBOX/EML migration guide is a good starting point.

Feature comparison#

Where Stellar Converter wins#

This is the kind of comparison where it's important to name where the competitor is genuinely the better pick.

Repair is what Stellar is built for. A 40GB PST from a decommissioned Outlook profile that won't mount cleanly is exactly Stellar's home turf. The engines have been refined for two decades on real corruption cases. Mailbox Taxi cannot help with a damaged file at all — it assumes the mail is reachable over IMAP.

Orphaned OST handling. OST files left behind when a user account is deleted from Exchange or Microsoft 365 are notoriously hard to recover from. Stellar's OST converter will pull readable mail out of these in cases where almost no other tool will. If you're triaging a leaving-employee scenario where IT has already revoked the account, Stellar may be the only practical option.

Granular format-to-format conversion. PST to MBOX, MBOX to EML, OST to PST — Stellar handles every combination natively. Mailbox Taxi's scope is live IMAP, not file format pipelines. If your project is exporting an old PST archive into individual EML files for an e-discovery vault, Stellar is what you want.

Familiar enterprise licensing. Stellar sells perpetual licences per technician, with optional upgrade subscriptions. For organisations that prefer capex to opex software, that's an easier purchase order to push through. Mailbox Taxi pricing has not been announced.

Forensic and preview features. Stellar's previewer lets you read individual messages inside a damaged file before recovery — useful when you're trying to decide whether the file is worth full repair effort. Mailbox Taxi has no analogous preview because there's no file in play.

For more on the file-recovery and conversion category, the PST conversion tools roundup covers Stellar in context with its peers.

Where Mailbox Taxi wins#

Live server-to-server migration at scale. This is the actual job most teams have most weeks: move mailboxes between live IMAP services. Mailbox Taxi was built for that — bulk CSV import, concurrency tuning, per-mailbox status reporting. Stellar's tooling doesn't address this case at all; it doesn't speak the wire protocol.

Cross-platform engineers. Your field engineer's laptop is a MacBook. Your automation host is a Linux VM. Stellar's mail tooling pushes you onto a Windows machine. Mailbox Taxi runs natively on all three. For an MSP with a mixed fleet, that is a meaningful workflow simplification.

OAuth2 done in-product. Gmail and Microsoft 365 increasingly require OAuth2 for IMAP access. Mailbox Taxi handles the consent flow inside the app, stores the refresh token securely, and refreshes silently during long-running migrations. Stellar's IMAP-export features support OAuth in some products and basic auth only in others; the matrix is uneven.

Resumable transfers. A 20-hour migration of a large mailbox is going to hit at least one transient network blip. Mailbox Taxi tracks last-confirmed UID per folder and picks up exactly where it left off. Stellar's conversion jobs are typically file-based and don't have the same resume semantics — though that's a different problem domain.

MSP-shape workflows. Multi-tenant runs, per-client folders of CSV inputs, exported reports for stakeholders. Mailbox Taxi's information architecture matches the way migration projects are actually structured. Stellar's UI is built around a single file at a time.

No file format gymnastics. If both source and destination are live IMAP, Mailbox Taxi never makes you convert into a file format and back. Stellar's workflow for the same scenario would mean exporting source to PST, then importing PST to destination — two conversions, two opportunities for fidelity loss.

For an adjacent comparison on the file-conversion side, see Mailbox Taxi vs SysTools and Mailbox Taxi vs Shoviv.

Pricing reality check#

Stellar's mail-conversion products are sold per-utility with a one-time licence fee, often with an annual upgrade subscription on top. A single converter is in the low three figures; the full Toolkit bundle is several hundred. Per-technician licensing means an MSP with five engineers multiplies that.

Mailbox Taxi is in waitlist phase and pricing has not been announced. Join the waitlist for early access and pricing details when the product launches.

A useful exercise: lay out your last twelve months of migration work and tag each project as "file-based recovery/conversion" or "live IMAP-to-IMAP move." That split tells you how much budget you should allocate to each category.

For the broader file-side glossary, the PST file entry covers the format itself in more depth.

Decision framework#

Pick Stellar Converter when:

• The mail you need to migrate exists as a file on disk — PST, OST, MBOX.
• The file is corrupted or orphaned and needs repair before anything else can happen.
• You're converting between archive formats for compliance, e-discovery, or long-term storage.
• Your team is on Windows and per-technician perpetual licensing is the right fit.
• You don't need bulk IMAP-to-IMAP transfers.

Pick Mailbox Taxi when:

• Source and destination are live IMAP services (Gmail, Microsoft 365, Zoho, Fastmail, cPanel, custom).
• You're moving more than a handful of mailboxes and want bulk CSV import.
• Your engineers run a mix of Windows, macOS and Linux.
• You want OAuth2 handled in-product with silent token refresh.
• The job is "move mail between servers," not "rescue mail from a damaged file."

Common errors and how each handles them#

A few that come up in real projects:

• OAuth2 token expired on a long-running 365 job. Mailbox Taxi refreshes silently. Stellar's behaviour depends on which utility — some prompt mid-job, some die.
• Too many simultaneous connections from Gmail. Mailbox Taxi backs off and throttles automatically. Stellar's IMAP-export feature surfaces the error and may need manual concurrency reduction.
• Corruption in a PST file. Stellar's repair engine handles this elegantly. Mailbox Taxi cannot open a PST file at all.
• Message too large for destination. Mailbox Taxi logs the message and lets you re-queue oversized items separately. Stellar, on the file side, doesn't usually face this problem because the writes are local.
• Orphaned OST after Exchange account deletion. Stellar can recover; Mailbox Taxi cannot.

A worked example#

Scenario one: a 20-mailbox cutover from a Zoho Mail tenant to a new Microsoft 365 tenant. Both endpoints live. Mailbox Taxi is the right tool. The engineer imports a CSV, runs the job over a Friday-night window, and exports a status report on Saturday morning. Stellar would force you through PST export and PST import, doubling the runtime and adding fidelity risk.

Scenario two: a 35GB PST file pulled off a retired user's hard drive, where the original Microsoft 365 account has been deleted. There's no live source to read from. Stellar Converter for PST opens the file, repairs any damage, and exports messages to MBOX or EML. Mailbox Taxi cannot help — there's nothing on the wire to pull.

Scenario three: a hybrid project. Twelve mailboxes are still live in Microsoft 365 and four are orphaned PSTs from departed staff. The clean pattern is Stellar for the four PSTs (export to a holding IMAP account or upload directly to 365 via a Stellar export utility), then Mailbox Taxi for the twelve live moves into the destination tenant.

That hybrid pattern is why most MSPs end up with both products in their kit.

What to test on your pilot#

For a Stellar pilot, pick a representative file:

1. Time to open a 20GB PST.
2. Fidelity of folder structure and read/unread state after conversion.
3. Behaviour on a deliberately-corrupted test file.
4. Output format options that match your destination's import requirements.

For a Mailbox Taxi pilot, pick a representative mailbox:

1. Time to migrate a 10GB mailbox end-to-end.
2. Behaviour during a deliberate network drop mid-transfer.
3. OAuth2 token refresh across a transfer longer than the token lifetime.
4. Bulk CSV import for 5 test mailboxes, run concurrently.

Treat each pilot as a separate exercise — the two tools aren't really substitutes.

FAQ#