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
Opera Mail offers a rich feature set with a customizable interface, making it suitable for users who prefer a desktop email client with extensive options. In contrast, K-9 Mail is an open-source mobile email client that focuses on security and simplicity, making it ideal for users seeking an efficient and straightforward mobile email experience.