Custom IMAP + Gmail
Custom IMAP via Fastmail, Migadu, Hetzner, your own server — connected alongside Gmail. STAMP triages both with the same shortcuts and replies from the right address.
OAuth where it works. App passwords where it has to. Native IMAP without the 'IMAP-mode' compromise.
Get early accessYour hosted domain is the address you actually own. STAMP treats it like the first-class account it is.
Replies leave from the wrong identity. STAMP picks the right one based on the originating thread, not based on which alias you remembered to select.
Mimestream is Gmail-only. Add an IMAP account and you're back in Apple Mail. STAMP handles both.
IMAP
Real IMAP support with proper threading, idle, and per-folder behaviour. Fastmail, Migadu, Hetzner, Postmark, your own server — all first-class.
Gmail
OAuth Gmail next to IMAP Fastmail. Both providers expose their best features. STAMP doesn't downgrade Gmail to IMAP just to make the two equal.
Aliases
Reply from the originating address every time. Multiple aliases on one IMAP domain? STAMP detects which alias the thread landed on and routes the reply through it.
“I run my own domain through Fastmail and a Gmail for everything else. STAMP is the first client that treats both equally.”
Early access user · Self-hosted enthusiast
There's a small but growing cohort of people who run their own domain through Fastmail, Migadu, or a self-hosted server. They do it for portability, privacy, or because they got burned by a Gmail policy change once. They also typically still have a Gmail because that's what their plumber uses.
Most modern email clients are built Gmail-first. Mimestream is Gmail-only. Superhuman is Gmail and Outlook only. Apple Mail handles IMAP but treats it like an inferior protocol — slower sync, broken push, no triage UX.
STAMP treats custom IMAP as a first-class account. The IMAP layer is fast, threaded correctly, and doesn't fall back to polling-only mode. Aliases work. Folders work. Push works on servers that support it. The unified queue treats your custom domain identically to your Gmail.
Threading is correct. IMAP threading is famously broken — clients sometimes group by subject and sometimes by reference header and sometimes by both. STAMP threads correctly using the message-id chain, which is what the protocol intended.
Folders round-trip. A folder structure on Fastmail looks the same in STAMP. Move a thread in STAMP and it moves on the server. Move it on the server and it updates in STAMP. No drift.
Aliases work. If you have hello@yourdomain.com and you@yourdomain.com on the same IMAP account, STAMP detects which one the thread landed on and replies from it. You don't pick from a dropdown.
Idle/push works. STAMP uses IMAP IDLE where the server supports it. New mail lands instantly. Where idle isn't available, STAMP falls back to short-poll without delaying the rest of the queue.
Connect Gmail via OAuth in 28 seconds. Connect Fastmail (or Migadu, Hetzner, your server) with an app password in 28 more. Both accounts now flow into the unified queue.
Morning: STAMP headline reads 'Six need attention. Three are from your domain. Three are Gmail.' Both providers, one queue.
You reply to a thread on hello@yourdomain.com. The reply leaves from hello@yourdomain.com. The recipient sees the address they expect. The brand consistency stays.
Searching is unified. Threading is consistent. Tags apply across providers. The cognitive load of 'where is this thread' goes to zero.
Yes, as long as they speak IMAP and SMTP. Mailcow, Mail-in-a-Box, custom Postfix setups — all work. Provide host, port, username, app password during setup.
JMAP support is on the roadmap. Today STAMP uses IMAP for Fastmail, which works well. JMAP will improve sync speed and battery life when it ships.
Yes. Configure SMTP host and port during setup. STAMP can also send through providers like Postmark or SendGrid if you've configured them as outbound relays.
STAMP is a paid subscription from $9 a month, locked for life on whichever plan you pick if you join the founding window.
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