Moving to new server. Email Notification not working

hi all.

i just move my website to new vps server. here the url : https://www.wundtshop.com
it’s a fresh new vps with no program at all. ( digital ocean vps )

and now my email notification not working anymore.
any package i should install?

thanks for your help.

https://www.ads-software.com/plugins/woocommerce/