smtpmail-smtp-user

smtpmail-smtp-user is a variable defined in `smtpmail.el'.
Its value is

nil

Documentation:
User name to use when looking up credentials in the authinfo file.
If non-nil, only consider credentials for the specified user.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.