I have a triggered email being sent when users submit an order. It typically works fine, with customers getting the necessary information in their emails. I've had reports of a few customers getting error messages, though, and I'm not sure how to troubleshoot this.
In my code, I send out the email via the API. If I get an error instead of a send, I tell the user the email wasn't sent and to print the page for their records. I plan to add some logging of the error message at this stage so I can hopefully capture whatever the error message is, but is there anything else I can do in the meantime to find out why some users aren't getting their emails? I looked through the reports and didn't see anything that would give me a list of emails that weren't sent. Does something like this exist?
The first thing that I would try is to create a Sendable Data Extension containing the fields and values that you are using in your API request.
Validate the email using the Sendable DE you created. If there are no errors, then use the Send Preview feature and preview the records in your DE — my guess is you're using AMPscript in your email and there's a data related issue where values are failing to render by the OMM process when the email is sent.