I installed a mail server using roundcube for appanel using digitalocean's ubuntu 20.4 vps but could not install it successfully, often getting the following errors: Installed the first time: received internal mail, mail from gmail or other services sent to but could not send Installed the second time: received internal mail but could not send and receive mail from gmail and other services? Everything was set up ok, when using send mail in the server, I got the error: "Some cloud vendors (such as Google, Amazon) close port 25 by default, and you need to contact the vendor to open port 25 before you can use the post office service normally" How to install it successfully, guys?

How to fix mail server??

aaP_mobadme

I installed a mail server using roundcube for appanel using digitalocean's ubuntu 20.4 vps but could not install it successfully, often getting the following errors:

Installed the first time: received internal mail, mail from gmail or other services sent to but could not send
Installed the second time: received internal mail but could not send and receive mail from gmail and other services?
Everything was set up ok, when using send mail in the server, I got the error:
"Some cloud vendors (such as Google, Amazon) close port 25 by default, and you need to contact the vendor to open port 25 before you can use the post office service normally"
How to install it successfully, guys?