spam email send to input admin

Hi,

after i use this plugin it have a lot of spam send to my mail. so i don’t know how to stop this spam. one day i got a lot of spam mail in inbox.

add more question, when I click on button submit it will redirect to home page. I don’t want like this. I want when click on submit it can stay in page form not link to another page.

Can you help me.
this is my website: http://www.patacambodia.com/?page_id=151

https://ww.wp.xz.cn/plugins/si-contact-form/