Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!

Expensify - Import expenses directly from a credit card to create free expense reports quickly. Approve reports online and reimburse directly to a checking account with one click.

Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.

Abacus - Expenses without the 'expense report'

eM Client - eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.

Zoho Expense - Automate your expense reporting process and streamline the approval flow.