Claws Mail is a free desktop e-mail client which is truly based on C/GTK. Released in 2001 and since it keeps improving and updating new things. Available for both Windows and Unix Systems. Fast and efficient. Claws Mail stores the emails in MH format.
During installation, you may see different plugins are available to add. If by chance, you didn't install them, then you must go back and download them first. Open up your add/remove software utility, search for "paws", find out the plugins available. You will see lots of plugins are available there. You must install one of them. This plugin allows you to choose a technique for Claws Mail to give you notice about the received e-mail.
For installing the theme for Claws Mail, first, install the latest version. After the installation, you have to move to the configuration > Preference > Display and then select the themes for it. Click any one of the themes, and click the install button.
Claws Mail for windows provides you space in one plane. So that you can access all of your e-mails from all accounts. It also provides you an option of sending and receiving emails from multiple accounts without login into one of them separately. The best thing is that it is totally free there is no paid version available with extra functionality.
But there are few drawbacks of the Claws Mail listed here;
There are two well-known alternatives of Claws Mail that can beat the software in a very well-mannered way. One of them is Mail.ru Agent. You can also consider Mailbird. The setup of Mailbird is easier. Mailbird supports 17 different languages so that users will feel comfortable using the software. The other alternative is eM Client. eM Client has a default spell checker or the setup is easier as like in Mailbird.