How to delete old messages automatically?

[Starmix]

I noticed I have thousands of messages unread including spam and I want to remove them automatically without clicking them one by one. They skow down the system. I delete 300 to 400 every day and I feel tired doing it. How I like, it's like deleting the spam and the sent messages in one click. I have to click them one by one and I am still in 2013 . Is there an easy way to remove them?

 

[eLdavis]

I am also having this issue on my email. So many massages that I don't need and I usually find it hard delete one by one

 

[Starmix]

It is a problem so numerous they're slowing my laptop. I'm still in 2013. I am deleting 300 messages daily.