I'm executing user-specific PHP code to register a user in a back-end system. In my Auto Action, I've selected the "Type" as "Code" and the "Trigger" as "onAfterUserRegistrationMailsSent". The "User" field of the AutoAction has to point to the user receiving the Registration email because I need to retreive other specific user fields for registration in the backend system. I've selected "User" as "Manual" and am using "variable 4". Does this context allow me to use substitution fields in my PHP program so that [cb:userdata field="email" /] would return the email address of the user receiving the Registration Email? I'm not sure where to find what the value of each of the "Manual" variables actually is. Can someone provide some clarity?

The autoaction I'd rather use is trigger('onAfterUserApproval', array( $user, true, true)), but I don't see how substitutions would work in that situation since the user is most likely the admin and not the user being approved. With 'onAfterUserApproval', is variable 1 the username of the user that's being approved? If $user is an array, then what are the array members?

What other variables are populated with user information for this trigger. Is username the only variable that's available without a lookup? For the user that's been verified, I ultimately need

[username]
[firstname]
[lastname]
[email]

Based on what I've read. These lines of PHP code will populate my variables with the user's information in my auto action code block. Or have I completely misunderstood:

$username = [username];
$cbUser =& CBuser::getInstance( $user->$username );
$my_email = getField( email, $defaultValue = null, $output = 'csv', $formatting = 'none', $reason = 'profile', $list_compare_types = 0 );
$firstname = getField( firstname, $defaultValue = null, $output = 'csv', $formatting = 'none', $reason = 'profile', $list_compare_types = 0 );
$lastname = getField( lastname, $defaultValue = null, $output = 'csv', $formatting = 'none', $reason = 'profile', $list_compare_types = 0 );