What is the best practice to create templates for outgoing email? Should I have each class create the html for the specific email? Should I have a text template with placeholders that are replaced by a common method?
In the first option, I'd have a sendEmail method that takes the formatted html string and send the email. Multiple classes would call this method after creating the html representation of the email.
In the second option, I'd envision having a number of text files like
<html>
<title>{emailTitle}</title>
Your user name is: {userName}
</html>
then a method that takes a hash map of keys, loads the appropriate text file and then replaces each key in the hash map with the value. This seems to have more flexibility as the code doesn't have to know anything about the html to create and you could change the email without changing code (only by removing values - adding a new key would require code changes).
What is the best practice to format email? Is there another option I should consider? I have to send four or five different types of emails - new registration, password reset, order confirmation, etc.
I am using Java, but the question is fairly language agnostic - some languages may make it easier for templating, but I'm asking about normal best practices.