From 2f9c7cd6d3652357cf6497fcac11fa1a2ec13aca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?G=C3=BCnter=20Obiltschnig?= <guenter.obiltschnig@appinf.com>
Date: Mon, 14 Jun 2021 19:13:48 +0200
Subject: [PATCH] #3219: SMTPClientSession: invalid SMTP command if empty
 recipients list in MailMessage

---
 Net/src/SMTPClientSession.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Net/src/SMTPClientSession.cpp b/Net/src/SMTPClientSession.cpp
index 9703f142e..4e6cdbc94 100644
--- a/Net/src/SMTPClientSession.cpp
+++ b/Net/src/SMTPClientSession.cpp
@@ -419,6 +419,7 @@ void SMTPClientSession::sendCommands(const MailMessage& message, const Recipient
 	std::ostringstream recipient;
 	if (pRecipients)
 	{
+		if (pRecipients->empty()) throw Poco::InvalidArgumentException("attempting to send message with empty recipients list");
 		for (const auto& rec: *pRecipients)
 		{
 			recipient << '<' << rec << '>';
@@ -429,6 +430,7 @@ void SMTPClientSession::sendCommands(const MailMessage& message, const Recipient
 	}
 	else
 	{
+		if (message.recipients().empty()) throw Poco::InvalidArgumentException("attempting to send message with empty recipients list");
 		for (const auto& rec: message.recipients())
 		{
 			recipient << '<' << rec.getAddress() << '>';
@@ -465,6 +467,7 @@ void SMTPClientSession::sendAddresses(const std::string& from, const Recipients&
 
 	std::ostringstream recipient;
 
+	if (recipients.empty()) throw Poco::InvalidArgumentException("attempting to send message with empty recipients list");
 	for (const auto& rec: recipients)
 	{
 		recipient << '<' << rec << '>';