If you'll expand a bit on your specification, we may be better able to help.

1. What does "outlook draft files" mean to you? Are you asking for a script and/or module to create draft text?
   • If so, how wide a range of possible content should the script be able to cope with -- a cover letter for a resume; a 'Dear John,' both, neither, or something else?
   • If not, are you asking for something that will generate what "Outlook" (© Microsoft; note the capitalization) calls a "draft"?
2. How will your "users" get access to the "button" -- in other words, are you talking about a website application involving user use of a browser? (And, just by the way, what's the relevance of the fact that you're "working on Linux." Are you merely trying to tell us you can't install Outlook on your local machine or is there some deeper significance?)
3. What do you mean by "a template file?" Is it the same as an "outlook draft" file?
   • One form of template is closely related to "boilerplate;" a phrase, sentence, paragraph or more of words which (are purported to) have a well-tested, well-defined meaning
   • On the other hand, your use of the phrase seems (to me, anyway) to imply that you expect some sort of digital binder to hold the text of the message. If so, you probably need to do a bit more study of how email works.
4. Why would a user with access to a computer want the capability about which you're asking? If they have that access, they probably have a local means to generate a message and send it without your intervention.

Update: Minor rephrasing... and, oh yeah, "send it" to whom? (Here, I'm making the perhaps incautious assumption that you do mean to "dispatch an email to one or more recipients. If not, please correct me.)