Okay, can see that the newsletter class no longer contains a Template_id field.

Would it be possible to get a updated walkthrough of how to send a mail programmatically

Did you get this sorted out yet yourself? I'm thinking of using NS and I need to be able to do this.

Yes, i sorted it out. Here is how i did it

var newsLetterRepository = new NewsletterRepository();

 // Create newsletter
                var ns = new Newsletter
                {
                    Name = "Name of mail visible in backoffice",
                    MessageBody = messageMarkup,
                    SubscriptionAlias = "Cyclone_0", // need to contain the unique name of the subscriptionlist. 
                    EmailSubject = "Email subject text",
                    EmailFrom = "test@test.com",
                    SenderName = "Testing",
                    Status = 0,//0=Created, 1=Initializing, 2=inProgress, 3=error, 4=completed, 5= paused
                    CreatedDate = datetimeNow, // Setting the date to now so it will be send right away
                    ScheduledSendDate = datetimeNow,
                    CreatedByUserId = 0,
                    SkinAlias = "Default"
                };
                newsLetterRepository.Save(ns);

//Calling newsletter endpoint to invoke newsletter sendout method
                var rootDomain = HttpContext.Current.Request.Url.Host;
                var newsletterEndpoint = "http://"+rootDomain + "/App_Plugins/NewsletterStudio/Pages/NewsletterCheckForScheduledSendOut.aspx";
                WebRequest webRequest = WebRequest.Create(newsletterEndpoint);
                webRequest.Method = "GET";
                webRequest.GetResponse();

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