1. In Memberships > Set up membership renewal notices, define a mail and email package for each time to expiration.
  2. At the bottom of the screen  in the "for patrons with no mail or email package preference" dropdown, choose the primary way you want to send this renewal  For example, select Email if you want to email everyone except for people without email addresses.
Altru will look at the person's constituent record.  If they have an email address and also have no communication preference, they will send them the email package.  If the person does not have an email, it will send the mail package.