Claws Mail is an open-source email client for Linux and Windows. It can become a new replacement for the older email clients that are no longer being developed. In fact the developers of Claws Mail have designed the program to be very user friendly specially for the users who have been using other popular email clients such as Mozilla Thunderbird or Microsoft Outlook.
When you launch Claws Mail for the first time, it will ask you to configure your email account and will not proceed without forcing you to add at least one account. Unlike Thunderbird, it does not have server settings for all the various email providers. It works perfectly for Gmail but for other email service providers, you will have to manually add the IMAP, POP2 or SMTP servers.
Furthermore, it does not support two factor authentication, so you may have problem with your email accounts if you have enabled two-factor authentication for them. One way around this problem is to use the app specific passwords generated in your email account to be used for Claws Mail – at least Gmail and Outlook provide this feature.
From the security viewpoint, Claws Mail offers many plugins that can detect and remove the spam email messages from your inbox. The SpamAssassin plugin can delete email messages identified as spam or move them to a designated folder and can also be used to train spam slashing capabilities. You can also configure the open-source antivirus ClamAV to scan the email messages for malware. For this, you have to install both the Clam antivirus on your PC and the Clam plugin in the Claws Mail client.
Claws Mail cannot compete with the immensely popular Mozilla Thunderbird in many fields, but it does give you a simpler alternative and works very smoothly without using many of your system resources.
You can download Claws Mail from https://www.claws-mail.org/.