diff --git a/lib/IMAP/MessageMapper.php b/lib/IMAP/MessageMapper.php
index 8503ed2738..b1ceaab744 100644
--- a/lib/IMAP/MessageMapper.php
+++ b/lib/IMAP/MessageMapper.php
@@ -35,11 +35,14 @@
 use Horde_Imap_Client_Socket;
 use Horde_Mime_Exception;
 use Horde_Mime_Headers;
+use Horde_Mime_Headers_ContentParam_ContentType;
+use Horde_Mime_Headers_ContentTransferEncoding;
 use Horde_Mime_Part;
 use Html2Text\Html2Text;
 use OCA\Mail\Attachment;
 use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Exception\ServiceException;
+use OCA\Mail\IMAP\Charset\Converter;
 use OCA\Mail\Model\IMAPMessage;
 use OCA\Mail\Service\SmimeService;
 use OCA\Mail\Support\PerformanceLoggerTask;
@@ -64,13 +67,16 @@ class MessageMapper {
 
 	private SMimeService $smimeService;
 	private ImapMessageFetcherFactory $imapMessageFactory;
+	private Converter $converter;
 
 	public function __construct(LoggerInterface           $logger,
 		SmimeService              $smimeService,
-		ImapMessageFetcherFactory $imapMessageFactory) {
+		ImapMessageFetcherFactory $imapMessageFactory,
+		Converter $converter) {
 		$this->logger = $logger;
 		$this->smimeService = $smimeService;
 		$this->imapMessageFactory = $imapMessageFactory;
+		$this->converter = $converter;
 	}
 
 	/**
@@ -943,15 +949,39 @@ public function getBodyStructureData(Horde_Imap_Client_Socket $client,
 				return new MessageStructureData($hasAttachments, $text, $isImipMessage, $isEncrypted);
 			}
 
+			// Convert a given binary body to utf-8 according to the transfer encoding and content
+			// type headers of the underlying MIME part
+			$convertBody = function (string $body, Horde_Mime_Headers $mimeHeaders) use ($structure): string {
+				/** @var Horde_Mime_Headers_ContentParam_ContentType $contentType */
+				$contentType = $mimeHeaders->getHeader('content-type');
+				/** @var Horde_Mime_Headers_ContentTransferEncoding $transferEncoding */
+				$transferEncoding = $mimeHeaders->getHeader('content-transfer-encoding');
+
+				if (!$contentType && !$transferEncoding) {
+					// Nothing to convert here ...
+					return $body;
+				}
+
+				if ($transferEncoding) {
+					$structure->setTransferEncoding($transferEncoding->value_single);
+				}
+
+				if ($contentType) {
+					$structure->setType($contentType->value_single);
+					if (isset($contentType['charset'])) {
+						$structure->setCharset($contentType['charset']);
+					}
+				}
+
+				$structure->setContents($body);
+				return $this->converter->convert($structure);
+			};
+
 
 			$htmlBody = ($htmlBodyId !== null) ? $part->getBodyPart($htmlBodyId) : null;
 			if (!empty($htmlBody)) {
 				$mimeHeaders = $part->getMimeHeader($htmlBodyId, Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
-				if ($enc = $mimeHeaders->getValue('content-transfer-encoding')) {
-					$structure->setTransferEncoding($enc);
-					$structure->setContents($htmlBody);
-					$htmlBody = $structure->getContents();
-				}
+				$htmlBody = $convertBody($htmlBody, $mimeHeaders);
 				$html = new Html2Text($htmlBody, ['do_links' => 'none','alt_image' => 'hide']);
 				return new MessageStructureData(
 					$hasAttachments,
@@ -964,11 +994,7 @@ public function getBodyStructureData(Horde_Imap_Client_Socket $client,
 
 			if (!empty($textBody)) {
 				$mimeHeaders = $part->getMimeHeader($textBodyId, Horde_Imap_Client_Data_Fetch::HEADER_PARSE);
-				if ($enc = $mimeHeaders->getValue('content-transfer-encoding')) {
-					$structure->setTransferEncoding($enc);
-					$structure->setContents($textBody);
-					$textBody = $structure->getContents();
-				}
+				$textBody = $convertBody($textBody, $mimeHeaders);
 				return new MessageStructureData(
 					$hasAttachments,
 					$textBody,
diff --git a/tests/Unit/IMAP/MessageMapperTest.php b/tests/Unit/IMAP/MessageMapperTest.php
index 057d96ca56..a45e3bef44 100644
--- a/tests/Unit/IMAP/MessageMapperTest.php
+++ b/tests/Unit/IMAP/MessageMapperTest.php
@@ -32,6 +32,7 @@
 use Horde_Imap_Client_Ids;
 use Horde_Imap_Client_Socket;
 use OCA\Mail\Db\Mailbox;
+use OCA\Mail\IMAP\Charset\Converter;
 use OCA\Mail\IMAP\ImapMessageFetcher;
 use OCA\Mail\IMAP\ImapMessageFetcherFactory;
 use OCA\Mail\IMAP\MessageMapper;
@@ -55,17 +56,22 @@ class MessageMapperTest extends TestCase {
 	/** @var ImapMessageFetcherFactory|MockObject */
 	private $imapMessageFactory;
 
+	/** @var Converter|MockObject */
+	private $converter;
+
 	protected function setUp(): void {
 		parent::setUp();
 
 		$this->logger = $this->createMock(LoggerInterface::class);
 		$this->sMimeService = $this->createMock(SmimeService::class);
 		$this->imapMessageFactory = $this->createMock(ImapMessageFetcherFactory::class);
+		$this->converter = $this->createMock(Converter::class);
 
 		$this->mapper = new MessageMapper(
 			$this->logger,
 			$this->sMimeService,
 			$this->imapMessageFactory,
+			$this->converter,
 		);
 	}