also netsuite's emailing system is not reliable so be careful when scripting with the API.. they even say so in their docs to use one of the API calls over the other if you want to "reliably deliver email".. but that may have changed?

Hey @creece can you dig out a link for this? We've had a few customers saying they've not received invoices (we're using a workflow to send email) but the communication history is disagreeing with them

its in the help for the email API