K-9 Mail icon
K-9 Mail icon

K-9 Mail

K-9 is an open source email client for Android with multi-folder sync, email signatures, Bcc-to-self, return-address configuration, keyboard shortcuts, Exchange Support, message flagging, IMAP deletes, saving attachments, configurable notifications and more.

K-9 Mail screenshot 1
K-9 Mail screenshot 2
+4
K-9 Mail screenshot 3

Cost / License

  • Free
  • Open Source

Application type

Platforms

  • Android
  • Android Tablet
  • F-Droid
K-9 Mail alternatives  
4.5
Excellent31 reviews
366likes
23comments
42alternatives
11news articles

Features

Suggest and vote on features

Properties

  1.  Configurable
  2.  Privacy focused
  3.  Lightweight

Features

  1.  Ad-free
  2.  IMAP Support
  3.  Multiple Account support
  4.  POP3 Support
  5.  One view multiple accounts
  6.  Unified inbox
  7.  PGP Encryption
  8.  Dark Mode
  9.  Works Offline
  10.  End-to-End Encryption
  11.  Encrypted Chat
  12.  No Tracking
  13.  Custom notifications
  14.  Contacts
  15.  GPG Encryption
  16.  Mail Filtering
  17.  OpenPGP
  18.  Spam Filter
  19.  Exchange
  20.  Email Organizer
  21.  Header sorting

 Tags

K-9 Mail News & Activities

Highlights All activities

Recent News

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Recent activities

  • CrossDaemon27 liked K-9 Mail
  • Diatomee reviewed K-9 Mail  
    ★
    ★
    ★
    ★
    ★

    My preferred email application for years now. It is reliable still gets recent updates

  • Diatomee liked K-9 Mail
  • peter-miller rated K-9 Mail  
    ★
    ★
    ★
    ★
    ★
  • peter-miller liked K-9 Mail
  • MyEzInbox icon
    Gerry-Haus added K-9 Mail as alternative to MyEzInbox
  • Maxwell8 liked K-9 Mail
  • Supamail icon
    amilasokan added K-9 Mail as alternative to Supamail
  • ottischmidt and Sebbxs liked K-9 Mail
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Comments and Reviews

   
 Post comment/review
Comment summary: K-9 Mail is praised for its simplicity, open-source nature, and ability to efficiently manage multiple email accounts without ads or tracking. Users appreciate its reliability, encryption options with OpenKeychain, and intuitive UI. However, some drawbacks include a lack of support for Outlook and Microsoft Exchange accounts, limited widget options, and issues with search functionality. The app remains popular despite funding challenges, maintaining a commitment to being a free and open-source project.
Top Positive Comment
Wayne Pierson
★
★
★
★
★
5

Easy and reliable open source android email app, have been using this as a daily driver for the last couple of years and have no problems.

Top Negative Comment
Miki Marshall
★
★
★
★
★
0

Works awesomely, until you need a subfolder in your Inbox (some email hosts insist), which K9 will not see at all. Unlike other apps, it seems K9 can only handle files OR subfolders, but not both.

NA0341

Subfolders work fine for me over IMAP (you need to tell it to rebuild the folder tree once a new one is added). What do you mean by "files"? Are you referring to the storage type? (I think it was one file per mail / one .mbox file with all mail.)

Diatomee
★
★
★
★
★
0

My preferred email application for years now. It is reliable still gets recent updates

ArafatZahran
★
★
★
★
★
1

Open source, free and very light on battery

NA0341
★
★
★
★
★
0

A great email client which just does what it's supposed to.

Good to know: The old UI is far superior in terms of productivity & acessibility - and there's lots of debate bc the devs have different opinions about the UI layout and ignore the users wishes (toolbar on top is the main issue).

If you want to try or use the old UI, the version is 5.600 (fully functional & stable; afaik the new versions have nothing notable v. 5.600 hasnt - maybe webDAV - support is new).

The screenshots display the old & new UI.

K0RR
★
★
★
★
★
1

It's the best open source Android email client but it's still way worse than the Gmail app.

The search is garbage, you can't edit it after sending the query.

There is no "Always show images from this sender" option.

Tubby 9417
★
★
★
★
★
1

Nice interface and easy to configure. Animations make the program feels slow so I disabled them. I prefer it over Fairemail

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7 of 23 comments

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What is K-9 Mail?

K-9 is an open source email client for Android with multi-folder sync, email signatures, Bcc-to-self, return-address configuration, keyboard shortcuts, Exchange Support, message flagging, IMAP deletes, saving attachments, configurable notifications and more.

K-9 Mail has been rebranded as Thunderbird for Android, but both versions are still available. Essentially, these two apps do not differ in functionality.

Official Links

AppStores & Other Links

Download from Google Play Store

K-9 Mail information

AlternativeTo Categories

Office & Productivity, Security & Privacy, Social & Communications

GitHub repository

  •  12,923 Stars
  •  2,668 Forks
  •  931 Open Issues
  •   Updated  
View on GitHub

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Our users have written 23 comments and reviews about K-9 Mail, and it has gotten 366 likes

K-9 Mail was added to AlternativeTo by JensKristian on and this page was last updated . K-9 Mail is sometimes referred to as k9mail, K-9, K9.