Following Sending Mail
Since no credentials are given in this configuration, Emacs will look them up in $(HOME)/.authinfo or $(HOME)/.authinfo.gpg (encrypted). The content of this file should follow this scheme:
machine example.org login [your login name] password [your password]
After finished the configuration and send mail
From: abst.proc.do@qq.com (abst.proc.do)
To: igabriel_job@163.com
Subject: Testing
Date: Wed, 22 Jan 2020 07:56:03 +0800
Message-ID: <874kwo2wks.fsf@foxmail.com>
--text follows this line--
Testing
but got the error:
gnutls-negotiate: GnuTLS error: #<process smtpmail<1>>, -15
What's the problem? I did not set gnus.
Ubuntu 19.10 emacs 26.3