K-9 Mail is an open source email client with support for multiple accounts, search, IMAP push email, multi-folder sync, flagging, filing, signatures. Developed by K-9 Dog Walkers
License: Open Source
K-9 Mail is an open-source email client with a focus on privacy and customization, making it ideal for tech-savvy users. In contrast, ALTO Mail offers a more user-friendly experience with built-in calendar integration, making it suitable for users who prefer simplicity and ease of use.