send-email: enable copying emails to an IMAP folder without actually sending them

`git imap-send` was built on the idea of copying emails to an IMAP folder
like drafts, and sending them later using an email client. Currently
the only way to do it is by piping output of `git format-patch` to IMAP
send.

Add another way to do it by using `git send-email` with the
`--use-imap-only` or `sendmail.useImapOnly` option. This allows users to
use the advanced features of `git send-email` like tweaking Cc: list
programmatically, compose the cover letter, etc. and then send the well
formatted emails to an IMAP folder using `git imap-send`.

While at it, use `` instead of '' for --smtp-encryption ssl in help
section of `git send-email`.

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config/sendemail.adoc

@@ -89,6 +89,7 @@ sendemail.smtpServerPort::
 sendemail.smtpServerOption::
 sendemail.smtpUser::
 sendemail.imapSentFolder::
+sendemail.useImapOnly::
 sendemail.thread::
 sendemail.transferEncoding::
 sendemail.validate::

Documentation/git-send-email.adoc

@@ -311,6 +311,20 @@ must be used for each option.
 This feature requires setting up `git imap-send`. See linkgit:git-imap-send[1]
 for instructions.
 
+--use-imap-only::
+--no-use-imap-only::
+	If this is set, all emails will only be copied to the IMAP folder specified
+	with `--imap-sent-folder` or `sendemail.imapSentFolder` and will not be sent
+	to the recipients. Useful if you just want to create a draft of the emails
+	and use another email client to send them.
+	If disabled with `--no-use-imap-only`, the emails will be sent like usual.
+	Disabled by default, but the `sendemail.useImapOnly` configuration
+	variable can be used to enable it.
+
++
+This feature requires setting up `git imap-send`. See linkgit:git-imap-send[1]
+for instructions.
+
 --batch-size=<num>::
 	Some email servers (e.g. 'smtp.163.com') limit the number of emails to be
 	sent per session (connection) and this will lead to a failure when

git-send-email.perl

@@ -62,7 +62,7 @@ git send-email --translate-aliases
     --smtp-user             <str>  * Username for SMTP-AUTH.
     --smtp-pass             <str>  * Password for SMTP-AUTH; not necessary.
     --smtp-encryption       <str>  * tls or ssl; anything else disables.
-    --smtp-ssl                     * Deprecated. Use '--smtp-encryption ssl'.
+    --smtp-ssl                     * Deprecated. Use `--smtp-encryption ssl`.
     --smtp-ssl-cert-path    <str>  * Path to ca-certificates (either directory or file).
                                      Pass an empty string to disable certificate
                                      verification.
@@ -75,6 +75,8 @@ git send-email --translate-aliases
     --smtp-debug            <0|1>  * Disable, enable Net::SMTP debug.
     --imap-sent-folder      <str>  * IMAP folder where a copy of the emails should be sent.
                                      Make sure `git imap-send` is set up to use this feature.
+    --[no-]use-imap-only           * Only copy emails to the IMAP folder specified by
+                                     `--imap-sent-folder` instead of actually sending them.
 
     --batch-size            <int>  * send max <int> message per connection.
     --relogin-delay         <int>  * delay <int> seconds between two successive login.
@@ -296,6 +298,7 @@ my $mailmap = 0;
 my $target_xfer_encoding = 'auto';
 my $forbid_sendmail_variables = 1;
 my $outlook_id_fix = 'auto';
+my $use_imap_only = 0;
 
 my %config_bool_settings = (
     "thread" => \$thread,
@@ -312,6 +315,7 @@ my %config_bool_settings = (
     "forbidsendmailvariables" => \$forbid_sendmail_variables,
     "mailmap" => \$mailmap,
     "outlookidfix" => \$outlook_id_fix,
+    "useimaponly" => \$use_imap_only,
 );
 
 my %config_settings = (
@@ -532,6 +536,7 @@ my %options = (
 		    "smtp-auth=s" => \$smtp_auth,
 		    "no-smtp-auth" => sub {$smtp_auth = 'none'},
 		    "imap-sent-folder=s" => \$imap_sent_folder,
+		    "use-imap-only!" => \$use_imap_only,
 		    "annotate!" => \$annotate,
 		    "compose" => \$compose,
 		    "quiet" => \$quiet,
@@ -1683,6 +1688,8 @@ EOF
 
 	if ($dry_run) {
 		# We don't want to send the email.
+	} elsif ($use_imap_only) {
+		die __("The destination IMAP folder is not properly defined.") if !defined $imap_sent_folder;
 	} elsif (defined $sendmail_cmd || file_name_is_absolute($smtp_server)) {
 		my $pid = open my $sm, '|-';
 		defined $pid or die $!;