Both Windows PC and Apple Mac come with an email app, but some people prefer third party software. There are a few apps and maybe you can name one or two, but have you tried Vivaldi Mail?
Vivaldi is best known for the web browser that is based on Chrome, but with tons of extra features built in, like better privacy options. However, it does more than just browse the web and it has a pretty good email client built in to it. Vivaldi can be used purely as a browser, just as an email client, or both. If you want an email client and don’t want to use Windows Mail or Apple Mail, Vivaldi Mail is worth looking at and is free.

When the latest version of Vivaldi is installed and run on the computer, you are given a choice of three versions, Essentials, Classic and Fully Loaded. Select the Fully Loaded version if you want to use the Vivaldi email client.
Add your email
Adding Gmail was easy and selecting Use OAuth in the setup box triggered the usual Google prompt to ask if you want to allow access to your email. Once permission is given, it downloads a copy of your emails. Outlook and iCloud is equally easy to set up.
If you have other email, there is a manual setup option where you enter the incoming and outgoing mail servers, username and password, and choose between POP3 or IMAP. Provided you have the info, Vivaldi Mail should work no matter what the email account.
Vivaldi email interface
The icons in the left toolbar are for accessing the different functions of Vivaldi and about half way down the list is the Mail icon with a badge showing the number of unread messages. The Vivaldi email client runs in a tab and both web browser and mail tabs can be open at the same time, which makes it easy to switch from one to the other.

The first column provides access to the mail accounts, folders, views, filters and so on. The second column lists email, such as the inbox, and shows the subject, date and time and sender. The third column is a preview pane that shows the selected email. The preview can be on the left or below the email list and there is a button to cycle through three different layouts.
Unread email counts are shown next to folders, but there is also a second number, which is Unseen. An email can be seen, but not yet dealt with for example, so Unseen and Unread counts can be different.

When creating new emails, they open in new tabs too. This is useful and not all email clients make it easy to switch between inbox and writing an email.
Use email views
There are many views in the first column and at the top are Unread, Received, Sent, Spam, Trash and more. Select one and the email list is populated with messages. Further down the column are individual email accounts and their folders. Select Unread for example and you see all unread emails in all inboxes, but select the Inbox for an account and it shows only that account’s inbox.
There is an auto-generated Mailing Lists section and Vivaldi Mail automatically groups some emails by sender. Select a Mailing List and all the emails it contains are listed.

If the search box is used to find emails, the search can be saved in the Filters section. So if you regularly search for emails from a particular sender or about a specific topic, there is no need to search again, the filter can be clicked to instantly see all the relevant emails.
There is a collection of colored flags and these can easily be attached to emails. Viewing all emails with a particular flag is then just one click. Labels can be attached to messages and they are added to a Labels section in the first column. Viewing all emails with a label is then just a mouse click.
There are many ways to view emails and they can make finding and organizing messages easier, if you can spare a few seconds to tag, flag and save searches.
Conclusion
Vivaldi Mail is free and comes with Vivaldi web browser if the Fully Loaded setup option is selected. It is a useful alternative to Windows Mail or Apple Mail for people looking for something a bit different. Its main benefit is the number of different ways that mail can be organized and viewed.
Emails are stored in a database and can be accessed and searched offline. Emails can be written and added to a queue to be batch sent later, which is useful if you are not online or want to send emails at a specific time.
Some email clients let you sleep emails or put them off until later, some remind you if you forget to deal with an email. Vivaldi lacks clever features like these, but it does do the basics very well.