SMF·MAILBIRD
Can a prompt replace Mailbird?
Email — email clients and hosted mail
Exhibit tracking slip
Verdict
A single-account IMAP client is already a fortnight. Merging three accounts into one list is where the genuinely fiddly parts appear: threads that span two accounts, replying from the right identity without thinking about it, and a unified sort order across mailboxes whose servers disagree about time. None of that is conceptually hard and all of it is the sort of thing you get wrong in ways that send a personal reply from a work address.
Exhibit A — The prompt
Received on31.07.2026Build a desktop email client whose defining feature is a correct unified inbox across several accounts.
Accounts: any number of IMAP and SMTP accounts, each with its own credentials in the OS keychain, its own identity (display name, address, signature) and its own colour used consistently throughout the interface. Support both password and OAuth authentication.
Sync: incremental IMAP per account with UIDVALIDITY and UIDNEXT tracking, resumable after a dropped connection, running concurrently across accounts without one slow server blocking the others. Per-account sync status visible.
Unified inbox, which is the point of this build and where the difficulty is:
- One list merging every account's inbox, sorted by the message's Date header normalised to UTC, not by server arrival order. Servers disagree, and mixing local and server time produces a list that reorders itself on refresh.
- Each row shows its account colour, so it is always obvious which mailbox a message came from.
- Threading operates across accounts: a message sent from a work address and a reply received at a personal one belong to the same thread if References says so. Group them, and mark clearly which account each message in the thread belongs to.
- Replying picks the identity of the account the message was received at, automatically, and shows which address it will send from before sending. When a thread spans accounts, reply from the account of the message being replied to, and make the identity switchable in one click.
Unified operations: archive, delete, mark read and search work across accounts, dispatching to the right server per message. A single search index covers everything, with a per-account filter.
Folders: per-account folder trees, plus unified virtual folders for common cases (all unread, all flagged, all sent) assembled from every account.
Safety: HTML rendered in a sandbox with remote images blocked by default, per-sender allow.
Also build: drafts saved to the correct account's server folder, attachments, and mbox export per account.
Out of scope: mobile apps and push, running a mail server, docking third-party web apps in a sidebar, and any AI feature.Opening prefills the prompt — press enter to run it.
Exhibit B — What you lose
- B.1 push notifications and a mobile client
- B.2 the app sidebar that docks other services next to the inbox
- B.3 provider-specific handling that keeps threading correct everywhere
- B.4 sync of read state and folders between machines
Prior art
Exhibit C — Why people still pay: mail infrastructure, integrations, and client polish
Because mail providers each break IMAP in their own way, and a client that behaves correctly against all of them is thousands of bug reports somebody else already filed.
Questions
Is there anything to migrate?
Mail stays on the servers, so nothing needs moving. Mailbird's account configuration and any docked apps do not transfer, but re-adding three IMAP accounts is a ten-minute job.
Why is unifying inboxes harder than it looks?
Because of identity and ordering. A unified list needs one true sort order across servers whose clocks and arrival times disagree, and every reply needs to leave from the right address without you checking. Getting the second one wrong is how a personal reply goes out from a work account, which is the failure that matters.
What does it cost to run?
Nothing beyond the accounts you already have. Everything is local; disk for the combined index is the only cost, and three large mailboxes with bodies indexed is a few gigabytes.
What is the one thing that does not survive the rebuild?
Provider quirks handled quietly. Every large provider bends IMAP somewhere — label semantics, folder naming, flag persistence — and Mailbird has absorbed a decade of those. Yours will be perfect with two providers and produce duplicate threads on the third.
Related tools
Receipt