What MailingServices API method should be used to send one-off or transactional campaigns?

Delivra's API offers transactional mailing service.  To use the TransactionalService, all campaigns must already be setup as Automated API campaigns in your account.  After these campaigns are created they can be referenced in your TransactionalService calls by ID. 

Below are the simple steps to create an API campaign in your account.

How-To

1. Navigate to the Campaigns dashboard.
   
   
2. Click the "Create New Campaign" button at the top-right of the page.
   
   
3. On the Setup step (Step 1) choose Automated Email as campaign type.
   
   
4. From the automated options, select API. 
   
   
   
5. Proceed with the rest of the Create a Campaign Workflow. 
   
   
6. Note the ID of the campaign from the Campaigns dashboard. Note: You may need to adjust your view in the dashboard to show the API campaign type.
   

Resources

Complete developer information for this service can be found here:
http://integration.delivra.com/delivraservices/documentation/TransactionalService.asp