we just newly installed Omeka S but are having problems with email sending to new users.
We are using Redhat servers and Postfix is working fine. What are the settings we need to change in the local.config.php file inorder to use Postfix?
Have you read the Mail section here : Configuration Options - Omeka S User Manual ?
Do you have logging enabled ?
If no, see Retrieving Error Messages - Omeka S User Manual
If yes, do you have any error messages related to email ?
In general if you have Postfix installed and working fine then no configuration is needed in Omeka S: the default is to use sendmail which should be using your Postfix setup. As Julian suggests if you’re having issues I’d check the Omeka and system logs.
If you have SELinux enabled sometimes you have to do a configuration to allow Apache/PHP to send email, just to throw out a random possible explanation of your issue.