Using smtp outside of ISPconfig for system emails

Hi,
Is there a way to define under System Config - Mail a SMTP that does not belong to the multi-server setup I got?
Let's say I want to use Gmail for example.
If I click SMTP auth then I have to fill the Default Mailserver which doesn't allow you to write your own.

Thanks

 

Try reading this: https://www.howtoforge.com/tutorial/configure-postfix-to-use-gmail-as-a-mail-relay/