Next step in my Postfix setup. How use it to send emails from website

Help! (Home for newbies)
1
SYSTEM INFORMATION
OS type and version Ubuntu 22.04
Virtualmin version 7

After I got help to configure the Postfix server I can now send mail from it and also send mail to it. What I now cant figure out is how to use it to send email from websites on the same vps. It is opencart and matomo that need to be configured with smtp settings but I cant find out how. I am sure the knowledge is here in the forum

2

The software you using should have docs on that normally. The prob using php mail to send the mail or using smtp to send, you could add a “mail user” to do that.
check open cart docs for example
https://docs.opencart.com/en-gb/system/setting/mail/
matomo

3

I have now all up and working but there is something strange. when the server send a mail it somehow mix in my email. from beginning my email was in the root alias file but I changed it to another address and restarted the postfix. But still when I get a mail from opencart, the only yhing I have up I get this.

anders.yuran@gmail.com: host gmail-smtp-in.l.google.com[142.250.27.26] said:
550-5.7.26 Unauthenticated email from gmail.com is not accepted due to
domain’s 550-5.7.26 DMARC policy. Please contact the administrator of
gmail.com domain 550-5.7.26 if this was a legitimate mail. To learn about
the DMARC initiative, 550-5.7.26 go to 550 5.7.26

k25-20020a50c099000000b0056e2db120d2si3688865edf.441 - gsmtp (in reply to
end of DATA command)

But I cant understand from where

4

I have no idea what you mean by this.

The error, though, indicates you don’t have DMARC configured correctly.