A family of Microsoft word processing software products for creating web, email, and print documents.
Which version of Office do you have? In most cases, you can just start the classic Outlook from the Windows Start menu. Pin a shortcut to the taskbar for easy access. The screen shot below is from Windows 10.
Also, you can set Outlook classic as the Windows default for e-mail. See https://support.microsoft.com/en-us/office/make-outlook-the-default-program-for-email-contacts-and-calendar-ff7990c4-54c4-4390-8fe3-c0285226f021.