Mail Quits in Time Machine

Part of the problem is you have an app that most experienced users on these forums consider malware, it is CleanMyMac. Please locate the developers uninstall instructions and please uninstall.

Mac OS is extremely secure and does not require any third party antivirus, cleaning or any third party "maintenance" apps. If simply kept up-to-date and otherwise left alone Mac OS will run well for most users for years. It is when users begin installing these types of apps that Mac OS becomes unstable, slow and creates weird issues like you are experiencing.

You also have something called CleanMyDrive installed. which may be part of CMM, so uninstall CMM first. If the CleanMyDrive apps is still installed you will need to uninstall that as well.

Finally, you have never upgraded the RAM. I would recommend upgrading by adding another 16GB of either Crucial.com or Macsales.com RAM. This will give the computer a total of 24GB of RAM, or enough to run well. You may see a slight improvement in speed.

Sounds like a conflict on your computer. Please do the following:

Please navigate to the Mac App Store or navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211

Your welcome.