send-email: explicitly disable authentication

It can be necessary to disable SMTP authentication by a mechanism other
than sendemail.smtpuser being undefined. For example, if the user has
sendemail.smtpuser set globally but wants to disable authentication
locally in one repository.

--smtp-auth and sendemail.smtpauth now understand the value 'none' which
means to disable authentication completely, even if an authentication
user is specified.

The value 'none' is lower case to avoid conflicts with any RFC 4422
authentication mechanisms.

The user may also specify the command line argument --no-smtp-auth as a
shorthand for --smtp-auth=none

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-send-email.txt

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 465a4ec..17993e3 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -190,7 +190,9 @@
 If at least one of the specified mechanisms matches the ones advertised by the
 SMTP server and if it is supported by the utilized SASL library, the mechanism
 is used for authentication. If neither 'sendemail.smtpAuth' nor `--smtp-auth`
-is specified, all mechanisms supported by the SASL library can be used.
+is specified, all mechanisms supported by the SASL library can be used. The
+special value 'none' maybe specified to completely disable authentication
+independently of `--smtp-user`
 
 --smtp-pass[=<password>]::
 	Password for SMTP-AUTH. The argument is optional: If no
@@ -204,6 +206,9 @@
 specified (with `--smtp-pass` or `sendemail.smtpPass`), then
 a password is obtained using 'git-credential'.
 
+--no-smtp-auth::
+	Disable SMTP authentication. Short hand for `--smtp-auth=none`
+
 --smtp-server=<host>::
 	If set, specifies the outgoing SMTP server to use (e.g.
 	`smtp.example.com` or a raw IP address).  Alternatively it can

git-send-email.perl

diff --git a/git-send-email.perl b/git-send-email.perl
index 2be5dac..a706794 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -82,8 +82,11 @@
                                      Pass an empty string to disable certificate
                                      verification.
     --smtp-domain           <str>  * The domain name sent to HELO/EHLO handshake
-    --smtp-auth             <str>  * Space-separated list of allowed AUTH mechanisms.
+    --smtp-auth             <str>  * Space-separated list of allowed AUTH mechanisms, or
+                                     "none" to disable authentication.
                                      This setting forces to use one of the listed mechanisms.
+    --no-smtp-auth                   Disable SMTP authentication. Shorthand for
+                                     `--smtp-auth=none`
     --smtp-debug            <0|1>  * Disable, enable Net::SMTP debug.
 
     --batch-size            <int>  * send max <int> message per connection.
@@ -341,6 +344,7 @@
 		    "smtp-debug:i" => \$debug_net_smtp,
 		    "smtp-domain:s" => \$smtp_domain,
 		    "smtp-auth=s" => \$smtp_auth,
+		    "no-smtp-auth" => sub {$smtp_auth = 'none'},
 		    "identity=s" => \$identity,
 		    "annotate!" => \$annotate,
 		    "no-annotate" => sub {$annotate = 0},
@@ -1241,7 +1245,7 @@
 # (smtp_user was not specified), and 0 otherwise.
 
 sub smtp_auth_maybe {
-	if (!defined $smtp_authuser || $auth) {
+	if (!defined $smtp_authuser || $auth || (defined $smtp_auth && $smtp_auth eq "none")) {
 		return 1;
 	}