From b36ed8eddb0e80a52956e5c5e46b1d07dc756b5d Mon Sep 17 00:00:00 2001
From: Bernhard Froehlich <decke@bluelife.at>
Date: Thu, 25 Feb 2021 21:15:16 +0000
Subject: [PATCH] net/smtp: adds support for the SMTPUTF8 extension

Obtained from:	https://github.com/golang/go/issues/19860
---
 smtp.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/smtp.go b/smtp.go
index c7557c3..a37d90c 100644
--- a/smtp.go
+++ b/smtp.go
@@ -242,7 +242,8 @@ func (c *Client) Auth(a smtp.Auth) error {
 
 // Mail issues a MAIL command to the server using the provided email address.
 // If the server supports the 8BITMIME extension, Mail adds the BODY=8BITMIME
-// parameter.
+// parameter. If the server supports the SMTPUTF8 extension, Mail adds the
+// SMTPUTF8 parameter.
 // This initiates a mail transaction and is followed by one or more Rcpt calls.
 func (c *Client) Mail(from string) error {
 	if err := validateLine(from); err != nil {
@@ -256,6 +257,9 @@ func (c *Client) Mail(from string) error {
 		if _, ok := c.ext["8BITMIME"]; ok {
 			cmdStr += " BODY=8BITMIME"
 		}
+		if _, ok := c.ext["SMTPUTF8"]; ok {
+			cmdStr += " SMTPUTF8"
+		}
 	}
 	_, _, err := c.cmd(250, cmdStr, from)
 	return err