Although it might seem they will all need different settings, the answer is probably not.
The info used by sendmail is really only the information needed to gain access to an SMTP server and forward the mail. Usually the applications or scripts actually format the e-mail (put it in a container) and provide the 'from', 'to' and any other e-mail addresses. SMTP is really a forwarding service, and you are telling the SMTP server (authenticating) that you have rights to use it to 'push' messages.
Remember SMTP stands for Simple Mail TRANSFER Protocol.
LOL - when you get to ten websites that are active, we can talk about how to run your own SMTP server (you'll only need one). And, by then, you probably will know a LOT more.