After the recurring mailing has been created it can be changed to a single mailing.

Alternative solutions:
  1. Create a new single mailing
  2. Schedule the mailing so that it is only delivered once:
    1. Navigate to Communications>Event Email Template
    2. Next to the Mailing Name click the Schedule button
    3. Under Schedule this Mailing, Select the Yearly radio button and enter the date the mailing should be sent (Daily, Weekly, Monthly can also be utilized)
    4. Under Starting: Select the date the mailing should be sent
    5. Under Ending: Select the radio button After __ Occurrences and enter 1
*This will ensure the mailing is sent on the desired date and only occurs once.

Also ensure the Approval Status has been selected, then click Save.