To purchase additional email credits:

Choose Direct Mail > Preferences...

Click the "e3 Delivery Service" toolbar icon.

Click Purchase Email Credit...
If your e3 Delivery Service account's credit balance is insufficient, you can purchase additional email credits.
Choose Direct Mail > Preferences...
Click the "e3 Delivery Service" toolbar icon.
Click Purchase Email Credit...
If the "Purchase Email Credit..." button is not visible, then your account is either disabled or is still under subscription billing and has not yet expired. Once your account expires, you will be able to purchase email credits.