Sterna Mail

Sterna Mail is an open-source email client for Android. It is intended for people who use one or more email accounts, including accounts hosted on JMAP servers and standard providers using IMAP and SMTP. JMAP is its primary protocol, while classic IMAP and SMTP are supported for broader provider compatibility. Account setup can use only an email address for autodiscovery, with manual server details and provider presets available when automatic configuration is not provided.

The app combines messages from multiple accounts in a unified inbox and keeps a local cache for offline reading and organisation. Multiple JMAP accounts can be managed under one login, with separate folders, notifications, and Sent copies for delegated, shared, or team mailboxes. Conversation threading, nested folders, configurable swipe actions, stars, archive and delete with undo, bulk selection, snoozing, spam reporting, sorting, and unread-only filtering support common mailbox tasks. Search provides immediate local results alongside server-side search, with filters for sender, subject, attachments, and date.

Sterna Mail supports recipient autocomplete, multiple identities with individual signatures, attachments, drafts, and replies that use the address receiving the message. It also provides undo send, scheduled sending, reminders for forgotten attachments or large recipient lists, and handling for mailto: links opened from other applications or browsers. Calendar invitations can be previewed as event cards and transferred to the device’s calendar app in one tap. New-mail notifications can use JMAP EventSource, IMAP IDLE, or UnifiedPush without Google services or FCM, with grouping by account and quiet hours, and the client also supports OpenPGP encryption.

Sterna Mail fits MirrorNest’s Android Email category as a client for both JMAP-based and conventional mail services. It is free software licensed under GPLv3 and does not require tracking, advertisements, analytics, or Google services. MirrorNest mirrors the official Android build directly on its own storage and scans it for malware before publishing. This distribution provides the catalog version while keeping the software aligned with the official build.