Does anyone know how to fix the whmcs smtp connection error? I entered it correctly but it didn't work

[bacdeptraivailon]

I use private hosting and I suspect it's because I installed fillware, but when I go to fillware csf, I see ports 465 and 587 and 25 are allowed. I don't know why it's wrong.

 

[justodishainfotek]

What mail server you are using? you need to give detail. Also provide version of whmcs