Do not send email by ojs

Our magazine system has recently had trouble sending emails to users. I talked to the site host and there is no problem with the site host. What should I do to solve this problem?
WhatsApp Image 2021-05-28 at 14.51.32

Hi @Aliakbar_Sajjadi,

Can you please indicate your OJS version that you are using and any steps that you’ve taken to address the issue so far? Also, you may wish to have a look at our guide on troubleshooting email here: Email

PKP Team

Thank you for your attention and response.
Our system version is
I called the host, he said that the problem is not with the host, follow the problem with OJS.