Use a table instead of multiple html with EmailService

I usually do this:

Email Service:

 public void NewScholarship(Boolean isApproved, String name, String classificationDescription, String percentage, String dateStarting, String dateEnding, String description)
    {
        Subject = isApproved ? "¡Beca creada!" : "No se pudo crear la beca";
        var templateText = isApproved ? GetTemplateHtml("NewScholarship.html") : GetTemplateHtml("Declined.html");


        templateText = isApproved ? templateText
                .Replace("{Name}", name)
                .Replace("{Percentage}", percentage)
                .Replace("{DateStarting}", dateStarting)
                .Replace("{DateEnding}", dateEnding)
                .Replace("{ClassificationDescription}", classificationDescription)
                :
                templateText.Replace("{Name}",name)
            .Replace("{Description}", description);
        EmailBody = templateText;
    }

Controller:

 using (var emailService = new EmailsService())
        {
            emailService.SetRecipient(student.Email);
            emailService.NewScholarship(false, student.Name, "", "", "", "", model.Description);
            emailService.SetSender(user, model.WithName);
            emailService.Send();
        }

After this I create an HTML template to send the mail (for each type of email). But my boss told me that this is not practical. And he told me to make a table and only an html file and depending on the user's request, the template will change the parameters.

For example, I have a Recovery Password and in my Html template I call these parameters:

{Username}
{URLrecovery}

And as I said before, I usually make another Html file for my Create Account, and I call these parameters:

{Username}
{Password}

But what my boss wants is that he only make an HTML file, and manage everything from the service and / or the controller. How do I send the parameters so that my template changes depending on the action? either CreateAccount or RecoveryPassword?