Unable to send or receive email in Roundcube webmail vesta

[wop]

My machine is centOS 7 and the instance is running on oracle cloud. I have installed Vesta on it and also installed the SSL.

I am trying to send emails. When I try to send it, it shows that It is sent but not actually sending it. Also, I am not receiving any email.

I am very new to this. Can you please help?

Thank you in advance.

I want to send and receive emails in Roundcube.