UTF-8 Encoding - Githubissues

Hi,

I am copying this from the WP support forum since I believe it is a bug.

We are noticing that the emails sent with WPMail SMTP are being wrongfully encoded. While the header shows they are encoded in UTF-8, wherever a non-UK language character is seen in the email, a few garbled texts is visible.

Date: Tue, 10 Aug 2021 18:08:17 +0000
From: =?UTF-8?Q?Parro=C4=8B=C4=8Ba_=C4=A6ad-DDDDDD?= <XXXXXXX@XXXX.org>
Bcc: pXXXXXg
Reply-To: XXXXXX@XXXXX.org
Message-ID: <2021010.34405847@smtp-relay.mailin.fr>
X-Mailer: WPMailSMTP/Mailer/sendinblue 2.9.0
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
To: XXXX@gmail.com
Subject: =?UTF-8?Q?Grazzi_tal-booking_tieg=C4=A7ek?=

Note: Subject: =?UTF-8?Q?Grazzi_tal-booking_tieg=C4=A7ek?=

We tried also to use the PHP Mail within the plugin, to double check whether it was SendGrid wrongly forcing the strange characters in the subject and elsewhere:

Date: Wed, 11 Aug 2021 10:33:52 +0000
From: XXX@gmail.com>
Reply-To: XXX@gmail.com
Message-ID: <XXXXXXXXXXXXhazsQU@mXXXXt>
X-Mailer: WPMailSMTP/Mailer/mail 2.9.0
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit
To: XX@XXX
Subject: =?UTF-8?Q?Booking_tal-Ikel_ming=C4=A7and_XXX_XXX?=

Note: Subject: =?UTF-8?Q?Booking_tal-Ikel_ming=C4=A7and_XXX_XXX?=

So we disabled the plugin altogether and voila, no UTF-8 issues:

To: XXX@XXX
Subject: Grazzi tal-booking tiegħek
Date: Wed, 11 Aug 2021 10:39:32 +0000
From: XXX@XX
Reply-To: XXX@XXX
Message-ID: <XXXXXXXXXXXXw@mXXXX>
X-Mailer: PHPMailer 6.4.1 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit

Note: Subject: Grazzi tal-booking tiegħek

Looking at above: both Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit are similar in all the 3 cases, so we are at a loss what could be going wrong. Do you have any pointers, please?

Any help is extremely appreciated

awesomemotive / WP-Mail-SMTP

UTF-8 Encoding #98