SIEVER Mail

Windows · Mac · Linux

Visit site Alternatives

Freedom report

One barScore 5.5

Runs widely3 of 6 device platforms
DocumentedThinly documented

SIEVER Mail is ranked #103 of 143 in email clients on Freedom251. It runs on Linux, macOS, Windows.

Compared on email clients

App coverage: desktop
Unified inbox: Yes

Best SIEVER Mail alternatives

See all 20

Three bars Mozilla Thunderbird Free tierOpen source No. 1Free9.5 Two bars Zoho Mail Free tier No. 2$0.08/mo8.3 Two bars Spark Mail Free tier No. 3$8.25/mo8.1 Two bars eM Client Free tier No. 4$3.33/mo8.1 Two bars Mailbutler Smart Assistant Free tier No. 5$7/mo8.1 Two bars Mailspring Free tier No. 6Free8.0

The record

Product: SIEVER Mail is an open-source desktop email client built with Electron.
Email support: It supports multiple IMAP/SMTP accounts and Gmail OAuth accounts in the same client.
Organization: Users can sort by date, sender, subject, or size; group messages; filter unread or flagged mail; and search with field-specific terms.
Layouts: It offers side-by-side folders, message list, and reader panes, or a dense table above the reader.
Message handling: The client supports replies, forwards, attachments, signatures, bulk actions, keyboard navigation, and light or dark themes.
Local data: Mail data is stored in a local SQLite database, and credentials are handled through the operating system keychain using Electron safeStorage.
Privacy: The project states that it has no telemetry or third-party tracking.
Security: The documentation says incoming HTML is sanitized with DOMPurify in sandboxed frames and opened attachments do not execute on click.
Connections: IMAP connections use SSL/TLS or required STARTTLS, and Gmail access uses OAuth 2.0 over IMAP/SMTP rather than the Gmail HTTP API.
Platforms: The build documentation lists macOS arm64 and x64, Windows x64, and Linux x64 and arm64 targets.
Extensions: A custom fork can attach one extension at build time, with hooks for toolbar actions, settings tabs, dialogs, IPC, and composer fonts and colors.
License and cost: The public project is released under the Apache License 2.0, and the opened project pages list no paid plans or trial.
Intended users: The maker describes it as originating with a small engineering team seeking a fast, focused client for multiple accounts and folders.
Maintainer and support: The repository says it is authored and maintained by Mattia Beltrami and welcomes issues through its GitHub tracker.

Where it ranks on Freedom251

Best Email Clients in 2026#103 of 143

Is SIEVER Mail yours?

Claim it for free: prove the domain, then correct facts, plans and screenshots. An editor reviews every change.

Claim it free Promote SIEVER Mail

Sources

github.com/beltromatti/siever-mail· checked 12 Oct 2026
github.com/beltromatti/siever-mail/blob/main/docs/· checked 12 Oct 2026