Extracting String from a text field in OTBI

Summary:

Hi all, I need to extract the last part of an email address so I can include the exceptions in a CASE statement.

Content (required):

What I need to do is extract any personal emails like @gmail, @outlook etc and leave them blank in a custom column leaving only email addresses with a work domain visible in the column.

So I would like to say:

CASE WHEN "Worker"."Employee Email Address" CONTAINS '@gmail' THEN ' '

ELSE "Worker"."Employee Email Address" END

This is for an OTBI leavers report that is currently set up.

Any help on this will be much appreciated.