diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 62908602e7..c8e55b2613 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -600,6 +600,28 @@ the name of the file that holds the e-mail to be sent.  Exiting with a
 non-zero status causes `git send-email` to abort before sending any
 e-mails.
 
+The following environment variables are set when executing the hook.
+
+`GIT_SENDEMAIL_FILE_COUNTER`::
+	A 1-based counter incremented by one for every file holding an e-mail
+	to be sent (excluding any FIFOs). This counter does not follow the
+	patch series counter scheme. It will always start at 1 and will end at
+	GIT_SENDEMAIL_FILE_TOTAL.
+
+`GIT_SENDEMAIL_FILE_TOTAL`::
+	The total number of files that will be sent (excluding any FIFOs). This
+	counter does not follow the patch series counter scheme. It will always
+	be equal to the number of files being sent, whether there is a cover
+	letter or not.
+
+These variables may for instance be used to validate patch series.
+
+The sample `sendemail-validate` hook that comes with Git checks that all sent
+patches (excluding the cover letter) can be applied on top of the upstream
+repository default branch without conflicts. Some placeholders are left for
+additional validation steps to be performed after all patches of a given series
+have been applied.
+
 fsmonitor-watchman
 ~~~~~~~~~~~~~~~~~~
 
diff --git a/git-send-email.perl b/git-send-email.perl
index fd8cd0d46f..66c9171109 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -795,11 +795,26 @@ if (@rev_list_opts) {
 @files = handle_backup_files(@files);
 
 if ($validate) {
+	# FIFOs can only be read once, exclude them from validation.
+	my @real_files = ();
 	foreach my $f (@files) {
 		unless (-p $f) {
-			validate_patch($f, $target_xfer_encoding);
+			push(@real_files, $f);
 		}
 	}
+
+	# Run the loop once again to avoid gaps in the counter due to FIFO
+	# arguments provided by the user.
+	my $num = 1;
+	my $num_files = scalar @real_files;
+	$ENV{GIT_SENDEMAIL_FILE_TOTAL} = "$num_files";
+	foreach my $r (@real_files) {
+		$ENV{GIT_SENDEMAIL_FILE_COUNTER} = "$num";
+		validate_patch($r, $target_xfer_encoding);
+		$num += 1;
+	}
+	delete $ENV{GIT_SENDEMAIL_FILE_COUNTER};
+	delete $ENV{GIT_SENDEMAIL_FILE_TOTAL};
 }
 
 if (@files) {
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 0de83b5d2b..6520346246 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -2326,6 +2326,37 @@ test_expect_success $PREREQ 'invoke hook' '
 	)
 '
 
+expected_file_counter_output () {
+	total=$1
+	count=0
+	while test $count -ne $total
+	do
+		count=$((count + 1)) &&
+		echo "$count/$total" || return
+	done
+}
+
+test_expect_success $PREREQ '--validate hook allows counting of messages' '
+	test_when_finished "rm -rf my-hooks.log" &&
+	test_config core.hooksPath "my-hooks" &&
+	mkdir -p my-hooks &&
+
+	write_script my-hooks/sendemail-validate <<-\EOF &&
+		num=$GIT_SENDEMAIL_FILE_COUNTER &&
+		tot=$GIT_SENDEMAIL_FILE_TOTAL &&
+		echo "$num/$tot" >>my-hooks.log || exit 1
+	EOF
+
+	>my-hooks.log &&
+	expected_file_counter_output 4 >expect &&
+	git send-email \
+		--from="Example <from@example.com>" \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--validate -3 --cover-letter --force &&
+	test_cmp expect my-hooks.log
+'
+
 test_expect_success $PREREQ 'test that send-email works outside a repo' '
 	nongit git send-email \
 		--from="Example <nobody@example.com>" \
diff --git a/templates/hooks--sendemail-validate.sample b/templates/hooks--sendemail-validate.sample
new file mode 100755
index 0000000000..640bcf874d
--- /dev/null
+++ b/templates/hooks--sendemail-validate.sample
@@ -0,0 +1,77 @@
+#!/bin/sh
+
+# An example hook script to validate a patch (and/or patch series) before
+# sending it via email.
+#
+# The hook should exit with non-zero status after issuing an appropriate
+# message if it wants to prevent the email(s) from being sent.
+#
+# To enable this hook, rename this file to "sendemail-validate".
+#
+# By default, it will only check that the patch(es) can be applied on top of
+# the default upstream branch without conflicts in a secondary worktree. After
+# validation (successful or not) of the last patch of a series, the worktree
+# will be deleted.
+#
+# The following config variables can be set to change the default remote and
+# remote ref that are used to apply the patches against:
+#
+#   sendemail.validateRemote (default: origin)
+#   sendemail.validateRemoteRef (default: HEAD)
+#
+# Replace the TODO placeholders with appropriate checks according to your
+# needs.
+
+validate_cover_letter () {
+	file="$1"
+	# TODO: Replace with appropriate checks (e.g. spell checking).
+	true
+}
+
+validate_patch () {
+	file="$1"
+	# Ensure that the patch applies without conflicts.
+	git am -3 "$file" || return
+	# TODO: Replace with appropriate checks for this patch
+	# (e.g. checkpatch.pl).
+	true
+}
+
+validate_series () {
+	# TODO: Replace with appropriate checks for the whole series
+	# (e.g. quick build, coding style checks, etc.).
+	true
+}
+
+# main -------------------------------------------------------------------------
+
+if test "$GIT_SENDEMAIL_FILE_COUNTER" = 1
+then
+	remote=$(git config --default origin --get sendemail.validateRemote) &&
+	ref=$(git config --default HEAD --get sendemail.validateRemoteRef) &&
+	worktree=$(mktemp --tmpdir -d sendemail-validate.XXXXXXX) &&
+	git worktree add -fd --checkout "$worktree" "refs/remotes/$remote/$ref" &&
+	git config --replace-all sendemail.validateWorktree "$worktree"
+else
+	worktree=$(git config --get sendemail.validateWorktree)
+fi || {
+	echo "sendemail-validate: error: failed to prepare worktree" >&2
+	exit 1
+}
+
+unset GIT_DIR GIT_WORK_TREE
+cd "$worktree" &&
+
+if grep -q "^diff --git " "$1"
+then
+	validate_patch "$1"
+else
+	validate_cover_letter "$1"
+fi &&
+
+if test "$GIT_SENDEMAIL_FILE_COUNTER" = "$GIT_SENDEMAIL_FILE_TOTAL"
+then
+	git config --unset-all sendemail.validateWorktree &&
+	trap 'git worktree remove -ff "$worktree"' EXIT &&
+	validate_series
+fi