Send email from your own domain with Resend, without leaving your desktop. Connect multiple accounts, compose rich-text messages, and optionally receive mail.
- Install OnlySend and connect your Resend account with OAuth or an API key.
- Follow the setup wizard to choose your domains and sender addresses.
- Compose and send. Enable receiving only if you want an inbox.
You need a Resend account and access to your domain's DNS settings. Sending requires a verified domain. Enabling receiving can redirect existing mail through new MX records; review the DNS instructions before changing them.
- Switch between accounts with separate mail and settings.
- Manage multiple domains, sender addresses, and DNS configuration.
- Compose formatted messages with attachments, CC, BCC, and Reply-To.
- Browse sent mail and an optional inbox with a dedicated reading pane.
- Search saved mail and filter by domain, including messages outside loaded pages.
- See previews of already downloaded messages without fetching each body again.
- Read downloaded message bodies offline, including after restarting the app. The footer shows local-copy progress and errors.
Email images, stylesheets, and fonts load automatically, including remote resources. Their servers may detect when you open a message. Sender scripts and forms remain blocked, and links open in your system browser. Remote resources are not saved for offline reading.
Received and sent messages show attachment cards. Click an image for a preview,
click a supported document to open it with the default application, or choose
Save as…. Downloads show progress and can be cancelled. PNG, JPEG, GIF and WebP
previews support files up to 5 MB; downloads support 25 MB per file.
Other file types, including executable files, HTML and SVG, must be saved rather
than opened automatically. Images referenced by cid: are loaded into the message
when available and are not repeated as attachment cards.
The composer uses the same cards, supports adding/removing files individually, and accepts 25 MB total. Image preview URLs are released when files are removed or the draft closes. Attachment bytes are prepared only when sending.
An attachment is downloaded once per session and reused for previews, external opening and Save as…, including offline. Missing or incomplete temporary files are downloaded again. The external viewer gets a separate working copy, reused within the session, so its edits cannot change the original attachment. Save as… in OnlySend always copies the original; use the external viewer's own Save as to keep edits before quitting OnlySend. The index lives only in Rust memory, not SQLite. OnlySend attempts to remove its private session folder and pending save temporaries when exiting; a crash or an external application's file lock can leave temporary copies behind. A new session needs to download again.
OnlySend checks connected accounts from Rust every 5 minutes, including when the window is minimized or another screen is open. In Settings → Notifications, choose 5, 10, 30 or 60 minutes, or turn automatic checks and notifications off. The Refresh button still works when automatic checks are off.
The first successful check establishes a silent baseline. Subsequent checks notify only new arrivals, with per-account checkpoints retained across restarts. Notifications display a count, not email contents. Failed checks back off rather than repeatedly hitting the API. System notification settings can suppress alerts.
OnlySend must remain running; quitting the app stops checks. Automatic checks fetch new inbox metadata, not the full archive on every interval. An explicit Refresh also retries the background archive download.
In Settings → Appearance, choose Light, Dark, or System (default). System follows your device's appearance, including changes while OnlySend is open.
Email avatars default to Blobavatars; choose Minimal to use initials. Avatars are generated locally from the displayed email address, so the same address has the same avatar in Inbox and Sent even when its display name changes. Appearance preferences are saved on this device and apply across accounts.
Release builds target Linux (.deb and .AppImage), Windows (.exe), and macOS
(.dmg, Intel and Apple Silicon). Download the matching file from
GitHub Releases.
Updater-enabled builds check once when opened. You can also use Settings → About → Check for updates. Installation is your choice; the app asks about unsaved drafts before closing. Debian installations use the package manager rather than the in-app installer.
macOS builds are not notarized and may require approval in Privacy & Security. Windows may show a SmartScreen warning. Older versions without the updater need one manual installation to receive in-app updates.
OnlySend uses Resend for sending and receiving; no separate OnlySend mail server is required. Downloaded messages are kept locally even if they disappear from Resend's lists. Disconnecting an account does not erase its local archive.
Local storage is not encrypted. The persistent mail archive includes message bodies and attachment metadata, not attachment files or remote images. Downloaded attachment bytes are kept separately in private session temporaries or saved by you.
For development, testing, and release instructions, see CONTRIBUTIONS.md.
Licensed under GPL-2.0-only.