diff --git a/git-send-email.perl b/git-send-email.perl
index 21b3686b2c..eb91270898 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -481,15 +481,21 @@ foreach my $t (@files) {
 	my $author_not_sender = undef;
 	@cc = @initial_cc;
 	@xh = ();
-	my $found_mbox = 0;
+	my $input_format = undef;
 	my $header_done = 0;
 	$message = "";
 	while(<F>) {
 		if (!$header_done) {
-			$found_mbox = 1, next if (/^From /);
+			if (/^From /) {
+				$input_format = 'mbox';
+				next;
+			}
 			chomp;
+			if (!defined $input_format && /^[-A-Za-z]+:\s/) {
+				$input_format = 'mbox';
+			}
 
-			if ($found_mbox) {
+			if (defined $input_format && $input_format eq 'mbox') {
 				if (/^Subject:\s+(.*)$/) {
 					$subject = $1;
 
@@ -514,6 +520,7 @@ foreach my $t (@files) {
 				# line 1 = cc
 				# line 2 = subject
 				# So let's support that, too.
+				$input_format = 'lots';
 				if (@cc == 0) {
 					printf("(non-mbox) Adding cc: %s from line '%s'\n",
 						$_, $_) unless $quiet;