If you import your short list into a table that's separate from your Main List table, you can link the two tables by Email address fields in your relationship graph. Then, on a layout based on your short list table, anyone not already in the Main List table will show an empty email field in the related Main List table.
You can pefrom a find to isolate these records by entering an * in this field while in find mode and selecting the Omit option.
In a script:
Go To Layout [Short List]
Enter Find Mode 
Set Field [Main List::EmailAddress ; "*" ]
Thank you for your reply.
Forgive my dumbness.
Can you point me to how to "import your short list into a table that's separate from your Main List table"
and also can you point me to how to "
"link the two tables by Email address fields in your relationship graph"
then how do I
make a "layout based on your short list table"
Thank you so much!
If someone wants to e-mail me at dk (at) purposeinc.com to show me how to do this, I am happy to pay for your time.
Thank you so much!
No need to charge for something that simple. ;-)
"...how to "import your short list into a table that's separate from your Main List table"
Go To Manage | Database | Tables, enter a table name such as "ShortList" and click create. Click the fields tab and define a field to match each field you need to import for this. (Might be just your email field, though I'd import at least a name field to double-check my matching. Creating a new table also creates a new layout with the same name as the table. To import data into this new table, select this "ShortList" layout and then choose Import Records from the field menu.
While still in Manage | Database, click the relationships tag and drag from your original email field to the email field in your new short list table. This links the two tables by email address fields.