DeletedUser622 The app is freeware now
"Freeware" only means that you don't have to pay money for it. Its still closed source and doing who the hell knows what like sharing your email password with the NSA.
What you're really looking for is "Open source", which is not just free, but also you can read the code to see what its actually doing. While you may not look at the code yourself, there are people who do, and the developers of significant open source projects don't want to be caught with backdoors or malware because that would destroy their reputation and their product's reputation. The bottom line is that bad stuff is a lot more likely to be discovered and corrected if it was placed intentionally into open source software vs closed.
There are TWO major open sourced email clients for Android;
- Fairemail
- K9Mail/Thunderbird