There are a few possible reasons why this may have happened. First of all, gift notification emails are not sent for offline unconfirmed gifts and will not be sent if they are confirmed after the fact. Gift notification emails will only be sent for offline gifts if they are created as confirmed.

Secondly, confirm that the participant is enabled to receive these gift notification emails.
  1. Select Fundraising > TeamRaiser
  2. Find your event and click Manage
  3. Find the participant and click their name
  4. Click Edit registration information
  5. Mark "Yes, send this participant gift notification emails"
  6. Click Save
Thirdly, confirm that the "Someone Made a Donation on Your Behalf" autoresponder is enabled in your event.
  1. Select Fundraising > TeamRaiser
  2. Find your event and click Edit
  3. Click Manage Autoresponders
  4. Locate "Someone Made a Donation on Your Behalf"
  5. Under the Version to Send, if it says "Do Not Send this Autoresponder," that means it is disabled
  6. Click either of the 2 options to enable it
    • If you see "Disable" then that means it is already enabled