Stop Mail app from Automatically Opening

[from 2013]

• Command-click (right-click) on the Mail icon if it's in your dock
• Hover over "Options" in the menu
• If "Open at Login" has a tick next to it, deselect it

OR

• Go to the "System Preferences"
• In the search box, start typing "login items" then choose it when it appears below
• Make sure Mail doesn't appear in that table, if it does, select it and choose the minus button at the bottom to delete it from the list

Also, make sure "Reopen Windows When Logging Back In" is unchecked.

If Mail isn't there, I'd say a something is calling upon it to open at Start-up

Where do you get most of you're apps from? Mac App Store or the internet?

System Preferences...>Users & Groups>Current User>Login Items

Check to see if Mail is set to launch at login.