With so many third-party applications available on the loose for all kinds of OSes including Android, iOS, Windows, and macOS, it is a mandatory step for the OEM/Software manufacturer to build a specific set of ‘default’ applications. The Mail application that ships with macOS and OS X is solid, feature-rich and spam-eliminating software that is also an easy-to-use email client. Optimized to work on the Mac, the Mail app is trouble free and full featured.
Mozilla Thunderbird is a free email program that offers a range of options for PC users without access to robust paid software like Microsoft Outlook. Allowing you to integrate multiple mailboxes with SMTP or POP protocols, Thunderbird is a lightweight, responsive piece of software that works well.
Pros
Open source and customizable: Because Thunderbird is developed by Mozilla, the group behind Firefox, it is more customizable than Outlook, a closed tool developed by Microsoft. At the same time, it offers all of the basics you need right out of the box, so you don't have to worry about highly complicated technical setup if you're not comfortable working in the trenches of a software tool.
Smarter organization: Thunderbird features a range of tools to make organizing your email as easy as possible. Including tabbed email browsing, smart searches, and custom folders to organize your messages, along with powerful spam filters that are better than a lot of Web-based tools, Thunderbird works well with most email services.
Cons
Desktop limitations: Because Thunderbird is a desktop tool for Windows, it doesn't synchronize directly with a mobile device natively. Yes you can set up a POP3 inbox so that all edits in Thunderbird appear at the server level, but it's an extra step that is required with tools like this. It's not unique, and the speed and flexibility of the software makes it a small complaint, but it's something to keep in mind if you compute on your tablet nearly as much as your desktop.
Bottom Line
If you don't like using relatively limited Web-based email tools, or if you'd like to further customize your browsing and organizational experience, Thunderbird is a must download. It's free, it has a number of available plug-ins and updates, and it's a perfect fit for almost anyone with multiple email accounts to manage.
What do you need to know about free software?
A free email client comes installed and ready for use with macOS, and macOS Mail is not a bad program at all. However, you might want to examine its free alternatives. Here are the best free email clients available for macOS. Give them a try.
MacOS Mail
What We Like
Included in the Mac operating system.
Supports smart folders and robust filters.
Markup tools for annotating photos or PDFs email attachments.
VIP user notifications.
What We Don't Like
Basic design that lacks customization features.
No option to snooze emails.
Hasn't had a major design upgrade in years.
The Mail application that ships with macOS and OS X is solid, feature-rich and spam-eliminating software that is also an easy-to-use email client. Optimized to work on the Mac, the Mail app is trouble free and full featured. It can handle all your email accounts in one place.
Spark
What We Like
Clean, modern design.
Quick Replies feature for sending short, templated responses.
Smart mailboxes.
Supports multiple email accounts.
Firefox Mozilla For Mac
What We Don't Like
Slow tech support.
Questionable privacy policy.
Doesn't support many services.
Spark is an impressive email program that auto-organizes your inboxes and lets you postpone email easily as well as send quick one-click replies. Spark's 'Smart Inbox' bubbles messages that are important to you to the top, and uses categories of Personal, Notifications, and Newsletters.
Spark's scheduling feature allows you to assign a time period during which it will send a particular message. Select from times later today, in the evening, tomorrow, or on any date.
Mailspring
What We Like
Integrates with Gmail, iCloud, Office 365, Outlook, and Yahoo
Supports snoozing.
CPU and battery efficient.
What We Don't Like
Some features limited to paid subscription.
Doesn't support Exchange accounts.
Mandatory Mailspring ID.
Aimed at the professional email user, Mailspring boasts mail merge, reminders, and the option to schedule mail—all available in a pro edition.
With the free version, you get a clean, highly productive and expandable email program that includes thrills such as link and open tracking, quick reply templates, and undo send. However, the free edition is limited to 10 accounts.
Mozilla Thunderbird
What We Like
Mozilla Thunderbird
Flexible filtering system.
Many available plug-ins.
Tabs for navigation.
Easy to configure.
What We Don't Like
Rudimentary design.
Not as user friendly as other clients.
No longer in development.
Mozilla Thunderbird is a full-featured, secure, and functional email client. It lets you handle mail efficiently and filters away junk mail. Thunderbird is no longer in active development except for security updates, but it supplies a streamlined interface and a powerful email package.
Mozilla SeaMonkey
Google Email Client For Mac
What We Like
All-in-one internet suite that includes email.
Customizable toolbars.
What We Don't Like
Outdated interface.
Some features not intuitive.
No mobile device support.
Thunderbird Email Client For Mac
Never underestimate Mozilla. The company built SeaMonkey, the email component of its open source browser, on the same Mozilla platform as Firefox 51. It delivers HTML5, hardware acceleration, and improved JavaScript speed. It is a solid performer, full featured and usable.