Overview

Aster Mail is an open-source email service with encrypted mail, custom domains and access to desktop mail clients through Bridge. It suits people who want a generous free mailbox and use Aster with other Aster users; its account-to-account encryption is a narrower promise than encryption for every message. The free plan is a credible starting point, while annual billing and the iOS beta are worth weighing before switching.

Key features

Encryption and privacy

Messages exchanged between Aster accounts are encrypted end-to-end automatically, with hybrid post-quantum encryption. That is useful protection for correspondence within Aster, but the stated encryption does not cover all mail regardless of recipient. Aster says its email is hosted in Germany under EU privacy law and that it has no ads, inbox scanning or AI on the inbox. There is no encrypted calendar, so users seeking a similarly protected calendar will need another service.

Bridge, migration and export

Aster Bridge supports IMAP and SMTP for desktop mail apps, giving users a way to keep using a compatible client. QuickSwitch can import mail from Gmail, Outlook, Yahoo, Proton and other IMAP providers, which lowers the friction of changing providers. Every plan includes free one-click mailbox export in MBOX format, a practical safeguard against being locked into one service.

Storage, aliases and rules

The free tier's 10 GB, five aliases, one custom domain and two mail rules make it more capable than a bare trial account, though the rule cap may constrain people who rely on automation. Star raises those limits to 50 GB, 15 aliases, five domains and unlimited rules; Nova expands to 500 GB, unlimited aliases and 30 domains. Supernova adds 5 TB and unlimited domains, but that capacity is excessive for many individual users.

Pricing

Aster is freemium, and the free plan lasts indefinitely with no trial requirement or credit card. Its 10 GB of encrypted storage, five aliases, one custom domain, two rules and Bridge access make it a useful way to assess the service without committing. Attachments are limited to 25 MB per message on the free plan.

Plan	Price and terms	What it includes
Free	0.00 USD per free	10 GB encrypted storage, 5 aliases, 1 custom domain, end-to-end encryption and Bridge access
Star	2.42 USD per month, billed annually; save 19%; final amount determined at checkout	50 GB, 15 aliases, 5 custom domains, unlimited rules and Bridge access
Nova	7.25 USD per month, billed annually; save 19%; final amount determined at checkout	500 GB, unlimited aliases, 30 custom domains, unlimited rules and Bridge access
Supernova	14.50 USD per month; final amount determined at checkout	5 TB, unlimited aliases and domains, unlimited rules and dedicated support

Star is the sensible upgrade for users who outgrow the free storage, alias or rule limits without needing Nova's large storage allocation. Nova suits heavier mail users or people managing many domains. Supernova is aimed at users who need 5 TB or dedicated support. Paid plans are billed annually, and the first paid plan has a 30-day money-back guarantee; renewals are excluded.

Platforms

Aster supports web, desktop and Android, with native desktop apps for Windows, Mac and Linux. Its iOS app is in beta on TestFlight, so iPhone users should be comfortable with beta software. Bridge adds desktop IMAP and SMTP access for those who prefer another mail app.

Who it's for

Aster is a good fit for people who value open-source software, want a custom domain and aliases on a free plan, or need Bridge, mailbox import and export. It is less compelling for users who need encrypted calendar, broad encryption beyond Aster-to-Aster mail, or a finished iOS app. Its independent maker, headquartered in Orlando and founded in 2026, says it has no VC investors.

Pros and cons

Pros

Useful free allowance: 10 GB, five aliases and one custom domain are included without a credit card.
Flexible desktop use: Bridge supports IMAP and SMTP, while native apps cover Windows, Mac and Linux.
Portability: QuickSwitch imports from major providers and other IMAP services, and every plan includes MBOX export.
Automatic protection within Aster: Account-to-account mail uses end-to-end, hybrid post-quantum encryption.

Cons

Encryption has a boundary: the end-to-end claim covers mail between Aster accounts, not every recipient.
No encrypted calendar: Aster does not provide one.
Free-tier constraints: two rules and 25 MB attachments per message may not suit demanding workflows.
Annual commitment: paid prices are billed annually, and the money-back guarantee does not cover renewals.
iOS is beta: iPhone users get a TestFlight beta rather than a generally released app.

Alternatives

Choose Proton Mail if its free plan's 1 GB storage and one email address fit your needs better than Aster's account-and-domain setup. Tuta Mail is another free option, with 1 GB storage and an included calendar, though Aster offers more free storage and custom-domain support. eclipso Mail Europe has a free plan with 4 GB storage, one address and no aliases, making it a simpler alternative if those limits are sufficient.

Mailo offers a free plan with 1 GB email storage, 500 MB for documents and photos, and five aliases, but includes ads. mail.de is worth considering if a free account with 500 MB storage, a 25-email daily limit and 60 MB attachments suits your needs. Mailfence has a free plan with 1 GB total storage, split between email and documents, and web access.

QeyeT is another email option to compare. SecureMyEmail is also an alternative.

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

Verdict

Aster Mail is best for privacy-minded users who want a substantial free mailbox, custom-domain support and desktop-client access, especially if they exchange mail with other Aster users. Its clear strengths are free storage, Bridge and easy export; look elsewhere if you need encrypted calendar, end-to-end coverage across all recipients, or a stable iOS release. For those trade-offs, the free plan is an appealing place to start.

	Aster Mail	Thexyz Email
Free plan	Yes	No
Free trial	No	No
Paid from	$2.42/mo	—
Open source	Yes	No
Platforms	Android, iOS, Linux, macOS, Web, Windows	Web, iOS, Android
Free plan	Yes	No
Mailbox storage	50 GB	10 GB
Email aliases	15 aliases	—
Paid from	—	2.95 /mo
Private calendar	—	Yes

Aster Mail vs Thexyz Email

Aster Mail

Thexyz Email