Some people say we should stop using desktop email clients. There are many reasons to say this. Web-based e-mail services have come a long way in the past decade, and many feature equally rich features with desktop-based alternatives. However, there are still many valid reasons for continuing to use desktop e-mail software, as e-mail clients are developing as the web ratio improves.
Postbox and Outlook are two basic options, but they are expensive. If you need an email client to handle one or two personal accounts, a free email client will probably serve well - just remember that as a free user, you can enter feature restrictions.
1. Thunderbird
Although Thunderbird development was stopped in 2012, it is still receiving maintenance updates. In fact, a stable version update was released earlier this year. It may not receive new features in the future, but it can certainly be used.
And as sad as I want to say, Thunderbird is actually the only free and open source desktop email client worth using.
2. Nylas Mail
We can specify Nylas Mail as an awesome mail client for Mac. Nylas Mail, announced in January 2016, is rapidly advancing on the path of growth, now ranked as one of the best mail clients.
3. Mailbird
They entered the market very quickly and called themselves outlook killer, but I can't see them on their site right now :) there is a serious number of users, I personally use it and I use plugins together with amazing whatsapp I would definitely recommend providing access to all platforms from the desktop. It is very fast in Imap but some errors occur as you use it. Update packages are useful in removing the results.
4. eM Client
eM Client aims to be an all-in-one solution for dealing with office tasks and communication. It is primarily designed for email, but has stylish calendar integration, task management, contacts organization and even chat support - and its free version only has a limitation (although large) below: see below.
In Free Version
Slick Modern UI interface that fits well with Microsoft apps.
Syncs with Gmail, Exchange, iCloud, Office 365, and Outlook.com.
Conversational view for email threads.
Integration with all common chat services, including Jabber.
Supports up to 2 email accounts.
In the paid version
Supports an unlimited number of email accounts.
Can be used for commercial purposes (e.g. business office use).
VIP support and troubleshooting.
Available for Windows.
5. Hiri
It aims to change the way you use your e-mails because your e-mail habits cause excessive stress and is designed to minimize how much time (thus increasing your daily efficiency) in "inconsistent" e-mails. It even reminds you not to check your email too often. If you are in a fear of efficiency, you need Hiri.