The list that the email is sent to will be adjusted automatically based on the members who are included in that group at the time and date you schedule the email to go out on. i.e. if you are sending an email to all your contacts, and schedule the email on January 1 to be sent on February 1, all the contacts in your system AS OF FEBRUARY 1 will receive the email. 

When you are in the compose email screen:

1. After composing the email, scroll down to the bottom of the page click Preview Email, the draft message will then be sent to the email address listed in the box Email Reply-To
   
2. Select who to email
3. Set Do you want to send this email now?
   
   • No = schedule a date and time to send
     
     • Click the calendar icon to select a date and time (Note: Time is based on Eastern Time Zone)
     • Set As Recurring Email Message
       
       • No = send immediately
         
         • Click Send Email button 
       • Yes = select Frequency options
         
         • Set Expiry of recurring message
         • Click Send Email button