From 4934aee8fb2421a4e58b22016800945cb0ac6c50 Mon Sep 17 00:00:00 2001
From: Dante Catalfamo <43040593+dantecatalfamo@users.noreply.github.com>
Date: Thu, 24 Apr 2025 09:00:35 -0400
Subject: [PATCH] Add `To:` header when constructing emails (#28507)

#28032
---
 changes/28032-email-to-header | 1 +
 server/mail/mail.go           | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 changes/28032-email-to-header

diff --git a/changes/28032-email-to-header b/changes/28032-email-to-header
new file mode 100644
index 0000000000..f33cba695d
--- /dev/null
+++ b/changes/28032-email-to-header
@@ -0,0 +1 @@
+- Fixed missing To: email header
diff --git a/server/mail/mail.go b/server/mail/mail.go
index bb741a43fa..277ab5b942 100644
--- a/server/mail/mail.go
+++ b/server/mail/mail.go
@@ -78,7 +78,13 @@ func getMessageBody(e fleet.Email, f fromFunc) ([]byte, error) {
 	if err != nil {
 		return nil, fmt.Errorf("failed to obtain from address: %w", err)
 	}
-	msg := []byte(subject + from + mime + content + "\r\n" + string(body) + "\r\n")
+	to := ""
+	if len(e.To) == 1 {
+		to = "To: " + e.To[0] + "\r\n"
+	} else if len(e.To) > 1 {
+		to = "To: undisclosed-recipients\r\n"
+	}
+	msg := []byte(subject + from + to + mime + content + "\r\n" + string(body) + "\r\n")
 	return msg, nil
 }