01The ghost-email problem
Somewhere in the last decade, the big free mail providers settled on the same idea: let the mailbox fill for years, then put a meter on it. Yahoo cut free storage to 15 GB in the UK and EU this year, with banners warning you may lose the ability to send and receive until you delete mail or start paying monthly.
Here is what bothered me enough to build something. Most of those bytes are not your correspondence. They are newsletters, promotions, alerts and receipts — most of which you never asked for. When you buy the extra storage, you are mostly paying rent on advertising that was sent to you. I started calling it ghost email, and once you see it you cannot unsee it.
My own Yahoo mailbox was the test case: 32.7 GB, with unread mail going back more than two decades. When Yahoo told me I was over the limit, that was the push. I wanted to clear the junk without handing my inbox to a web service that would read it.
02What Mailroom does
Mailroom is a local-first desktop app for Windows and Linux. It scans the mailbox on your own machine and sorts everything into three piles: safe to clear, keep, and needs your review.
The important part is what it reads. Mailroom reads the envelope — sender, size, date, and attachment names, types and sizes. Never the message body, and never the file contents, and never by shipping your mailbox to a server to be read. The scanning and sorting all happen locally.
It is independent and not affiliated with Yahoo. Yahoo is the supported provider today; more providers are planned.
03The two hard problems
Two things turned out to be much harder than I expected.
Recognition
Bulk mail does not identify itself. The first version of the classifier — I call it KeepSafe — could only call about 2 GB of my 32.7 GB safe. Newsletters fragment across ever-changing subjects; personal mail hides among bulk; a localized folder name (a French Envoyés folder, in one early build) quietly broke Sent-folder detection. And Sent detection matters, because of one rule I refuse to relax: mail from anyone you have ever emailed is never marked safe to delete.
Months of tuning against several real, old mailboxes got it to reclaim far more on mine, with everything uncertain landing in the review pile instead of the delete pile. The review pile is not a defect — it is the reason the delete pile can be trusted.
Speed
The first full scan of that mailbox took about an hour and a half. Nobody trials an app that wants 90 minutes before it shows anything. The same mailbox now scans in roughly 16 minutes: batching the IMAP metadata fetches properly, precomputing the aggregates the interface actually asks for, and a design that rescores incrementally when you change a setting instead of rescanning the whole mailbox.
04The honest trade-offs
The awkward parts, upfront, because you will find them anyway:
- It is closed source. Paid licences are how the project pays for itself. What I offer instead is a claim you can check at the protocol level: Mailroom speaks standard IMAP, and per message it reads only metadata — never the message body, never the file contents. Put a TLS-intercepting proxy on your own machine and read the session yourself; what you see will match that promise. The privacy notice enumerates every small thing that does leave your device.
- The installer is self-signed, so Windows SmartScreen shows an “unknown publisher” warning. A certificate authority costs real money and the app has to earn it first. SHA-256 hashes for every download are on the download page.
- It connects with a Yahoo app password. I know what handing a mail credential to a stranger’s app means. That is exactly why local-only processing is the whole product, not a feature — an app password is revocable in one click and scoped to mail only.
It is Yahoo-only today because Yahoo users are the ones being squeezed hardest right now. I would rather ship one provider done properly than several done badly.
05Try it
The trial is the full app — no card, no account. It scans everything and shows exactly what it recommends removing and why, and lets you really delete, so you judge it on real results rather than a demo. If it earns it, a licence is a one-time yearly licence — no subscription, no auto-renew, no card stored by us.
Prefer to just grab the installer? Download Mailroom → · New to the storage problem? How to free up Yahoo Mail storage.