How do I stop email and texting from starting when I open safari on my mayfair?

Check Apple Menu > System Settings > General > Login Items? Typically you would not have any applications open on startup, but if you wanted to, they can be added here. To remove them, just select and click the "-".

You can also right click on the app in the Dock and go to Options > Open at Login. If it is checked, then unchecking it will stop it from opening on startup.

Let us know what you have tried. Is it just opening in Safari that causes it or is it rebooting? Unclear between the title and message. Have you tried Safari Extensions, Launch Agent folders in System Library, Malwarebytes, EtreCheck, Startup Items in the ~/Library folder?

As you know, it is not normal behavior, so we have to start with the obvious without any further information.