--- title: K-9 Mail Reviews meta_title: 'K-9 Mail Reviews 2026: Details, Pricing, & Features | G2' meta_description: Filter 13 reviews by the users' company size, role or industry to find out how K-9 Mail works for a business like yours. aggregate_rating: rating_value: 4.5 review_count: 13 scale: '5' date_modified: '2026-05-05' parent_category: name: Collaboration & Productivity url: https://www.g2.com/categories/collaboration-productivity --- # K-9 Mail Reviews **Vendor:** Opensource **Category:** [Email Client Software](https://www.g2.com/categories/email-client) **Average Rating:** 4.5/5.0 **Total Reviews:** 13 ## About K-9 Mail K-9 is an opensource email client based on the Email application shipped with the initial release of Android. K-9 is focused on making it easy to chew through large volumes of email. ## K-9 Mail Reviews ### 1. Private, open-source email **Rating:** 5.0/5.0 stars **Reviewed by:** Skyler G. | Software Engineer, Mid-Market (51-1000 emp.) **Reviewed Date:** May 28, 2023 **What do you like best about K-9 Mail?** K9 is by far the best email client I've found for Android. I'm glad for its open-source nature as it helps to be secure in the knowledge that my email is not being listened-in-on, as well as other more advanced features such as E2EE via PGP encryption. **What do you dislike about K-9 Mail?** K9 color schemes can affect the readability of email. For example, if you set emails to be read on a dark background, some text may also be set to a dark color and not be changed by K9. It would be nice if K9 could change the text color so it had more contrast no matter what the email specified. **What problems is K-9 Mail solving and how is that benefiting you?** K9 lets me use multiple email accounts with privacy-enhancing features, all with a free and open-source client. Unlike competitors like Gmail, K9 doesn't display ads in my inbox or read my email. It's simple, and that's great! ### 2. Excellent option to management of POP3 and IMAP. **Rating:** 5.0/5.0 stars **Reviewed by:** Encio B. | Analista mayor de servicios tecnicos de Licencias de Gas, Enterprise (> 1000 emp.) **Reviewed Date:** November 14, 2018 **What do you like best about K-9 Mail?** It's simple to use and it has a lot of options to configure your emails. **What do you dislike about K-9 Mail?** User interface should be a little more modern or clean. **What problems is K-9 Mail solving and how is that benefiting you?** I use it to configure and manage my personal and business email in one single app. ### 3. Mail client. **Rating:** 4.0/5.0 stars **Reviewed by:** Verified User in Design | Small-Business (50 or fewer emp.) **Reviewed Date:** January 04, 2018 **What do you like best about K-9 Mail?** One of the few email clients POP and IMAP, for Androida. In my opinion, the most adequate. **What do you dislike about K-9 Mail?** Not very convenient to use. The interface is more convenient for the program Agua Mile. I would like the developer to listen to the wishes of users. **Recommendations to others considering K-9 Mail:** I recommend for use as an alternative email client. **What problems is K-9 Mail solving and how is that benefiting you?** It is convenient for me to send mail from my smartphone. ### 4. Highly recommended **Rating:** 4.0/5.0 stars **Reviewed by:** Verified User in Events Services | Small-Business (50 or fewer emp.) **Reviewed Date:** January 04, 2018 **What do you like best about K-9 Mail?** Ease of use and the ability to merge all emails in one place **What do you dislike about K-9 Mail?** There is nothing wrong with the application **Recommendations to others considering K-9 Mail:** Definitely give it a try!! **What problems is K-9 Mail solving and how is that benefiting you?** Ease of email use ### 5. K9 mail: The best android mail client **Rating:** 5.0/5.0 stars **Reviewed by:** Verified User in Biotechnology | Mid-Market (51-1000 emp.) **Reviewed Date:** January 24, 2017 **What do you like best about K-9 Mail?** K9mail handles multiple accounts easily, notifications are trivial to set up, and of course the entire app is open source. It is updated fairly frequently- every month or two, usually. There are no major features which are absent, and it can be used with any mail server which supports IMAP or POP. It has built-in support for PGP encryption as well, using an app like OpenKeychain. **What do you dislike about K-9 Mail?** The search function of the app could definitely use some work- if there were a way to more easily search the remote server for old emails, that would be useful. But this can be worked around by starring emails I think I'll need later for ease of search. **Recommendations to others considering K-9 Mail:** K9mail is a phenomenal free and open-source email client for mobile devices. Certainly more featureful than most default email clients, I highly recommend this to anyone who cares about freedom when choosing which apps they want to run on their device. It's stable, it works well, and you will have few complaints. **What problems is K-9 Mail solving and how is that benefiting you?** This makes it easy to keep in touch with my job and receive emails from my phone when I'm on the move. ### 6. Solid app for Exchange email **Rating:** 4.5/5.0 stars **Reviewed by:** Greg K. | Technical Support & Software Trainer, Translation and Localization, Small-Business (50 or fewer emp.) **Reviewed Date:** July 27, 2016 **What do you like best about K-9 Mail?** The layout is clean and simple to use. It allows me to keep up to date with my work emails while on the go. **What do you dislike about K-9 Mail?** I don't seem to be able to import all of my folders. I have sub-folders within my Inbox, but they don't appear on the app (while other exchange apps will show everything). **Recommendations to others considering K-9 Mail:** It's a great app for POP3, IMAP, and Exchange email accounts. It's great for basic use, but if you use it for a work account that has a lot of sub-folders, it may not work for you. **What problems is K-9 Mail solving and how is that benefiting you?** Keeping up to date with work emails while away from my computer. ### 7. Simple E-Mail App that Works **Rating:** 4.0/5.0 stars **Reviewed by:** Chris M. | Camera, Grip, and Lighting Departments, Entertainment, Mid-Market (51-1000 emp.) **Reviewed Date:** April 01, 2016 **What do you like best about K-9 Mail?** I first downloaded K-9 Mail when my Android's pre-installed e-mail client wouldn't work, and have been using it for everything except my personal G-mail ever since. The app is simple with very little in the way of frills, and it just works. **What do you dislike about K-9 Mail?** The biggest annoyance is trying to search for e-mails that have since been deleted locally. Currently, only e-mails that are on the device are searchable, so if you want to search beyond the 50 or so still stored locally, you have do download past e-mails, 50 at a time, which then show up as unread. If there was a way for the app to search the server and only download e-mails matching he search criteria, the search function would be much more useful. **Recommendations to others considering K-9 Mail:** If you're looking for something with a lot of features, look elsewhere. If you want an app that is simple and just works, then this is it **What problems is K-9 Mail solving and how is that benefiting you?** K-9 lets you combine multiple e-mail accounts into one, easy to use, highly intuative client, and just works when others don't ### 8. Great for free but has some rough edges **Rating:** 4.5/5.0 stars **Reviewed by:** Verified User in Individual & Family Services | Mid-Market (51-1000 emp.) **Reviewed Date:** October 15, 2016 **What do you like best about K-9 Mail?** Free, supports multiple inboxes and IMAP and POP3 **What do you dislike about K-9 Mail?** Old look and feel (GUI), need to manually purge and compact mailboxes **Recommendations to others considering K-9 Mail:** It's free so there's no harm in installing. Just keep an eye on storage and purge folders. **What problems is K-9 Mail solving and how is that benefiting you?** Email access on smartphones (Android) ### 9. K9 mail review **Rating:** 4.0/5.0 stars **Reviewed by:** Verified User in Health, Wellness and Fitness | Enterprise (> 1000 emp.) **Reviewed Date:** January 05, 2016 **What do you like best about K-9 Mail?** It was fast and accurate. It felt as if it retrieved my mail before my phone would. **What do you dislike about K-9 Mail?** There was some issues like compatibility using it with a galaxy note 4. It did not like cooperating on my phone with my other programs. Felt like I was constantly getting doubles of emails and when I tried to delete it on K9 it wouldn't transfer over to my mailbox on other devices. **Recommendations to others considering K-9 Mail:** Use their support it helped majorly with the doubling of mail issues but I still feel as though it didn't play very nice with the Android OS. **What problems is K-9 Mail solving and how is that benefiting you?** We wanted a mail client that worked efficiently both by way of the desktop and on different smartphones as apps. I realized that we needed something that we could go to and did not have to look in multiple places for. A one place for all mail but better then the standard client on phones. ### 10. Best open source email client **Rating:** 5.0/5.0 stars **Reviewed by:** Verified User in Pharmaceuticals | Enterprise (> 1000 emp.) **Reviewed Date:** August 25, 2016 **What do you like best about K-9 Mail?** Open source client which is very efficient and able to handle large volumes. **What do you dislike about K-9 Mail?** Not much to dislike. Only thing concerning is security of the software visavis Android security issues. **What problems is K-9 Mail solving and how is that benefiting you?** Fast and very efficient platform ### 11. All in one mail. Does what it sets out to! **Rating:** 5.0/5.0 stars **Reviewed by:** Ketan B. | Small-Business (50 or fewer emp.) **Reviewed Date:** March 10, 2016 **What do you like best about K-9 Mail?** I can integrate all my emails in one app. Easy to set up and the UI is not cluttered. Also since it is so minimal, takes up less RAM and is responsive. **What do you dislike about K-9 Mail?** A little bit work on the UI would have helped, it is too barebones at the moment. **What problems is K-9 Mail solving and how is that benefiting you?** I have 3 different mail accounts from different providers. K9 lets me get all their mails in one place. ### 12. Gmail alternative for unified inbox **Rating:** 4.5/5.0 stars **Reviewed by:** Joseph C. | Software Developer, Computer Software, Small-Business (50 or fewer emp.) **Reviewed Date:** December 10, 2015 **What do you like best about K-9 Mail?** I really enjoy the ability to import email addresses from multiple hosts. Email filters are also really useful, but not really any better than gmail's option. The stability and support from developers is incredible, and puts it miles ahead of other software that might look more polished. **What do you dislike about K-9 Mail?** I dislike the default signature, but that's about it. The user interface is not as nice as CloudMagic, but the support and stability more than make up for it. Most everything else is great! **Recommendations to others considering K-9 Mail:** Do it! You might be "wow-ed" by the slick user interface of CloudMagic, but don't be fooled! k9mail has far superior support, has been stable for years, and best of all, is FREE! Best email client on Android! **What problems is K-9 Mail solving and how is that benefiting you?** I am solving the need to manage multiple email inboxes from a single device; K9mail does the job wonderfully. It has never crashed on me, and stability is a huge requirement of running multiple email accounts. ### 13. A very good open-source alternative to android mail **Rating:** 4.5/5.0 stars **Reviewed by:** Eugene C. | Partner, Venture Capital & Private Equity, Small-Business (50 or fewer emp.) **Reviewed Date:** October 01, 2012 **What do you like best about K-9 Mail?** Instead of using the android gmail client, using k9mail allows me to get emails one by one (rather than grouped into threads) which works well in certain cases. The interface is efficient and effective. There are also a host of interaction settings -- such as gesture control, flipping through items using volume controls, etc., -- that make this a really good mail client because actions can be much more atuomated **What do you dislike about K-9 Mail?** It doesn't support most free hotmail accounts and does have quirks with exchange **Recommendations to others considering K-9 Mail:** If you don't have touchdown exchange, I've heard that k9mail is a great alternative. In my own experience with k9mail, I think it's a much improved version of the default android mail client. I'm inclined to be using this even over the gmail client on my phone. It's opensource, so I expect it will continue to improve with time ## K-9 Mail Discussions - [What is K-9 Mail used for?](https://www.g2.com/discussions/what-is-k-9-mail-used-for) - [View K-9 Mail pricing details and edition comparison](https://www.g2.com/products/k-9-mail/reviews?section=pricing&secure%5Bexpires_at%5D=2026-06-27+10%3A13%3A19+-0500&secure%5Bsession_id%5D=d65f636d-fd81-4064-bf55-a17088d18c35&secure%5Btoken%5D=7777b5a299bda4d944e36c14a5e4bcf8823edec55b0e92c86d6b2b1b8406e35c&format=llm_user) ## K-9 Mail Features **Inbox Tools** - Unified Inbox - Filters - Reminders - Notifications **Coordination Tools** - Calendar - Contacts - Task Management **Software Options** - Desktop Application - Mobile Application **Email Client - Agentic AI** - Autonomous Task Execution - Cross-system Integration ## Top K-9 Mail Alternatives - [Microsoft Outlook](https://www.g2.com/products/microsoft-outlook/reviews) - 4.5/5.0 (3,410 reviews) - [Thunderbird](https://www.g2.com/products/thunderbird/reviews) - 4.3/5.0 (334 reviews) - [BlueMail](https://www.g2.com/products/bluemail/reviews) - 4.3/5.0 (48 reviews)