Thunderbird, Microsoft Office Outlook, Apple Mail, Mailbird, Evolution, Postbox, eM Client, EssentialPIM, Mutt, iRedMail, Geary, Microsoft Mail and Calendar, Gmail Notifier Pro, PopTray, PopTrayU, Pegasus Mail, Calypso, PopMan, POP Peeper, Mia for Gmail, Mailnag, GNOME Gmail, Claws Mail, Mail Notification, GMDesk, Gmail Peeper, GmailAssistant, Gmail Manager, Gmail™ Notifier +, MetroMail, Gmail Notifr are some alternatives to NPOPuk.