The sort menu is the location you'll go to when wanting to presort your list, index it on a predefined or custom field, and more.
Presort Mail - Takes you to the Presort Setup screen, where you can select your presort parameters and set your mailing preferences.
By Last - Indexes your list by Last Name for viewing purposes.
By Company - Indexes your list by Company for viewing purposes.
By Address - Indexes your list by Address for viewing purposes.
By Zip Code - Indexes your list by Zip Code for viewing purposes.
User Defined - Takes you to the User Defined Sort screen, where you can create custom viewing filters. Index your list by multiple fields and selections, in ascending or descending order, if you so desire.
Delete Indexes - Delete any active indexes that have been built for your current database.
Rebuild Indexes - Recreate any active indexes that have been built for your current database.