non-interactive authentication

[woodz-]

It seems the auth-client documentation is lacking some parts like setting the interaction callback and the description, how authentication interaction works in general.

I am looking for a way to bypass interactive authentication and instead use credentials hard coded or obtaining them from env.

Is there some support and documentation doing so?

[libesmtp]

Looks like auth_set_interact_cb() is missing documentation.

Usage is pretty straightforward - the declarations in the header files and example/mail-file.c should give enough information to write a suitable callback. struct auth_client_request provides information on the required response. Depending on the SASL mechanism the callback may be called multiple times.

The auth interact callback need not be interactive depending on application requirements. The application callback might prompt the user for a response, look up a configuraion variable or make a database query etc. libESMTP itself does not care how the application obtains the response, only that it obtains it.