Mailbird first came to my attention six or seven years ago and, until I adopted Postbox, as my de facto email client. Even so, I still keep Mailbird on my PC to keep up with how the service is evolving as it regularly crops up in the lists of top email clients alongside Outlook, Thunderbird and others. As such, it is in good company.
Postbox Email, Power And Flexibility

Aqua Mail Gets My Perfect Email Vote
Aqua Mail has completely ruined the old epithet that it is better to travel than arrive. Over the years I have liked nothing better to try out a wide range of Android email apps and finding their strengths and weaknesses before moving onto the next one. Aqua Mail has screwed that by being the best email app I have come across and will probably always be my email app of choice. The reasons are many and varied.
First, Aqua Mail has so many configuration options you will be lost for choice, well around 300 choices to be accurate. Whether it is changes in the interface you want to make or the way the app itself handles emails, there is an option that you will eventually find that suits you. I say eventually, because it took me several weeks of tweaking to get it just right.
Spark Email Doesn’t Light My Fire
Lockdown boredom means that I am always looking around for new apps and services, especially email apps, and that is how I came across Spark which, on the face of it, looked to be very promising. However, as I experimented with it, it became clear that Spark and I were never going to be friends. This doesn’t mean it is a bad email package, just that the way I work with email and Spark didn’t have matching personalities or methodologies.