automatic e-mail sender - configurable "canned responses" or plugin to customize NopCommerce email templates

We are a mobile phone line rental service and when a client does not pay the bill we need to send an email to the mobile carrier requesting that the line be blocked so that it can't be used. Depending on the carrier (we work with 2 carriers) we need to send the request to a different email address and with a different body template that contains our basica company information and what we need to be done. We will need basic email templates like "interrupt service to phone number xxxxxxxx" or "remove interruption of service to phone number xxxxxx" and we need to inform the carrier (email to send to ) and the message (template - block unblock etc) and the number of the line that should be blocked sometimes may be multiple lines. We need to be able to request this email programatically (get api rest possibily) informing the carrier, default message and phone numbers. The templates need to be customizable and we need to be able to add new email templates and customize them. It helps to customize the "email subject" to be able to put phone number in email subject What we need is very similar to the "canned responses" that exist for gmail and outlook and other email programs so if we have a simple configuration page where we would create the templates, and have the variables that would resolve our needs. We imagine that MANY programmers have already done a "canned response" type software so I explained it in this way. NopCommerce Plugin - Currently we use NopCommerce so if we could generate from the email template a new email template to be sent under certain conditions (payment is late) or more importantly be able to trigger it programatically this would be ideal. Source code should de delivered in C# Any other questons please feel free to ask. We will send the programmer who is awarded the project emails, smtp etc. thanks Marcio