Aster Mail

Overview

Aster Mail is an open-source email service for people who want account-to-account encryption, custom-domain support and the option to use a desktop mail client. It suits privacy-minded users moving from another provider, especially those who need broad desktop coverage. Its generous free storage and migration and export tools make it worth considering, though its encryption is specified for messages between Aster accounts and its paid prices are billed annually.

Key features

Encryption and privacy

Mail between Aster accounts is end-to-end encrypted automatically, with hybrid post-quantum encryption. That is a meaningful safeguard for conversations within Aster, but it should not be mistaken for a promise that every message to every recipient is end-to-end encrypted. Aster says its email is hosted in Germany under EU privacy law and that it does not use ads, scan the inbox or apply AI to it. There is no encrypted calendar, so users seeking an encrypted email-and-calendar package should look elsewhere.

Mail apps, migration and export

Aster Bridge supports IMAP and SMTP for desktop mail apps, giving users an alternative to relying solely on Aster's own interface. QuickSwitch imports mail from Gmail, Outlook, Yahoo, Proton and other IMAP providers, which lowers the friction of moving an existing mailbox. One-click mailbox export in MBOX format is free on every plan, a useful safeguard against being locked into the service.

Storage and account limits

The free plan's 10 GB, five aliases and one custom domain are substantial starting allowances, but two mail rules may constrain users with more involved inbox workflows. Paid tiers expand those limits: Star raises storage to 50 GB, aliases to 15 and domains to five, with unlimited rules; Nova offers 500 GB, unlimited aliases and 30 domains; Supernova adds 5 TB and unlimited domains. Users who need several domains or high storage should compare tiers against their actual needs rather than paying for spare capacity.

Pricing

Aster uses a freemium model. Free is $0.00 per free, forever, with 10 GB encrypted storage, five aliases, one custom domain, end-to-end encryption and Aster Bridge. It is available without a credit card or trial commitment; attachments are capped at 25 MB per message and mail rules at two. That makes it a credible entry tier, though the rules and attachment cap may be limiting for heavier use.

Star costs $2.42 a month, billed annually, with 50 GB storage, 15 aliases, five custom domains, unlimited mail rules and Bridge. The stated annual discount is 19%, and the final amount is determined at checkout. This is the natural upgrade for an individual or small setup outgrowing the free limits, but the annual billing commitment matters.

Nova costs $7.25 a month, billed annually, and increases storage to 500 GB, aliases to unlimited and domains to 30, while retaining unlimited rules and Bridge. It fits users with larger mail archives or multiple domains; the added capacity is unnecessary for someone comfortable within Star's limits.

Supernova costs $14.50 a month, billed annually, for 5 TB, unlimited aliases and domains, unlimited rules and dedicated support. It is the tier for unusually large storage needs or support requirements, rather than a default choice. Aster offers a 30-day money-back guarantee on the first paid plan; renewals are excluded.

Platforms

Aster supports web, Windows, Mac and Linux desktop apps, and Android. The iOS app is in beta on TestFlight, so iPhone users should account for its beta status. Aster Bridge adds desktop IMAP and SMTP compatibility for users who prefer another mail application.

Who it's for

Aster is a strong fit for users who want encrypted communication with other Aster accounts, a custom domain, and a practical route to migrate into and export mail from the service. The no-card free tier makes it easy to assess against real needs. It is less compelling for people who need encrypted calendar features or expect account-to-account encryption to cover messages to any provider.

Pros and cons

Pros: The free plan combines 10 GB encrypted storage, five aliases, one custom domain and Bridge access without requiring a card.

Pros: QuickSwitch imports from major providers and MBOX export is free on every plan, making migration and departure more practical.

Pros: Native desktop apps cover Windows, Mac and Linux, alongside web and Android access.

Cons: Automatic end-to-end encryption is specified for mail between Aster accounts, not as a universal property of all outgoing mail.

Cons: The free plan has only two mail rules and a 25 MB attachment limit per message.

Cons: iOS remains a TestFlight beta, and there is no encrypted calendar.

Alternatives

Consider Proton Mail if you want another freemium provider with web, desktop and mobile platforms; its free plan includes 1 GB storage and one email address, far less than Aster's free storage and alias allowance. eclipso Mail Europe is another freemium option with Android, iOS, Mac, web and Windows support. Tuta Mail is worth comparing if its free tier's included calendar is a priority; it offers 1 GB storage and end-to-end encryption. Disroot Email is a free option with web and broad platform support, IMAP, SMTP, SMTPS and POP, plus optional PGP encryption with Mailvelope. Mailo offers a freemium service across Android, iOS and web, with IMAP4 and EAS access on its free plan. QeyeT is a paid service with a free preview and web, Windows, Linux, iOS and Android access. mail.de has freemium plans and supports web, iOS and Android. Mailfence is another freemium option for web and mobile users.

For broader comparisons, see Secure Email Providers, Private Email Services and Email providers.

Verdict

Choose Aster Mail if you want a generous free starting allowance, direct migration and export tools, and desktop options ranging from native apps to IMAP/SMTP clients. The main reason to look elsewhere is that its automatic end-to-end protection is framed around Aster-to-Aster mail, with no encrypted calendar and an iOS app still in beta.