mail automatically starts on macos 10.14

I am running MacOS 10.14 on an iMac. Upon startup every day, Apple's Mail application and Adobe's Acrobat Reader automatically start up and open windows before anything else happens. I never use Mail, and rarely use Acrobat Reader, so I must close them each morning. I have been unable to find a setting that would automatically start them upon firing up the computer, so that I could turn off this setting. If anybody knows why they are automatically starting and how I might turn them off, I would appreciate knowing. Thank you.