There are several benefits to using a free email client on a Mac, including:

1. Cost: As the name implies, free email clients don’t cost anything to download or use.
2. Customization: Many free email clients allow users to customize the interface and features to their liking.
3. Compatibility: Free email clients are often compatible with a wide range of email services, including popular ones like Gmail, Yahoo, and Outlook.
4. Productivity: Some free email clients come with built-in tools to help users organize and prioritize their emails, making it easier to stay on top of their inbox.
5. Security: Some free email clients include security features such as end-to-end encryption to protect users’ data.

However, there are also some cons to using free email clients, including:

1. Limited features: Some free email clients may have fewer features than paid options.
2. No customer support: Free email clients typically don’t offer customer support, so users will have to rely on online resources for help.
3. Potential for data mining: Some free email clients may collect data on users’ email habits and browsing history for targeted advertising.
4. Lack of integration with other apps: Some free email clients may not integrate well with other apps, such as calendar and contact apps.
5. Some free email clients may not be as reliable as paid options.

It’s important to research and compare different options to find the best free email client for your needs.

Top 5 Free Email Clients for Mac

1. Apple Mail: Apple Mail, also known as “Mail” or “Mac Mail,” is a built-in email client for Mac computers. It is designed to work seamlessly with other Apple products and features, such as iCloud and Spotlight search. It also offers a variety of tools for organizing and managing emails, such as rules, smart mailboxes, and VIP contacts.
2. Mozilla Thunderbird: Mozilla Thunderbird is a free and open-source email client for Mac, Windows, and Linux. It features a customizable interface, built-in spam filtering, and support for multiple email accounts. It also offers a variety of add-ons and extensions that can enhance its functionality.
3. Spark: Spark is a free and powerful email client for Mac and iOS. It is designed to help users focus on the most important emails by highlighting them, and offers a variety of tools for organizing and managing emails, such as snoozing, quick replies, and reminders. It also includes a built-in calendar and team collaboration features.
4. Mailspring: Mailspring is a free and open-source email client for Macbook pro 16 inch, Windows, and Linux. It offers a variety of features such as a built-in calendar, snooze and follow-up reminders, and the ability to schedule emails to be sent later. It also includes a built-in spell-checker, support for multiple email accounts, and a unified inbox view.
5. Mozilla SeaMonkey: Mozilla SeaMonkey is a free and open-source Internet application suite for Mac, Windows, and Linux. It includes an email client, web browser, and HTML editor, as well as other tools for web development. It is a successor of the Mozilla Application Suite, which was the original version of Mozilla Firefox and Thunderbird.

Please note that these are not the only free email client for Mac, there are many other options are available such as Airmail, Postbox, and eM Client.