diff --git a/externals/mimemailparser/__init.php b/externals/mimemailparser/__init.php
new file mode 100644
--- /dev/null
+++ b/externals/mimemailparser/__init.php
@@ -0,0 +1,11 @@
+<?php
+$root = __DIR__;
+require_once $root.'/Contracts/CharsetManager.php';
+require_once $root.'/Contracts/Middleware.php';
+require_once $root.'/Parser.php';
+require_once $root.'/Charset.php';
+require_once $root.'/Attachment.php';
+require_once $root.'/Exception.php';
+require_once $root.'/Middleware.php';
+require_once $root.'/MiddlewareStack.php';
+require_once $root.'/MimePart.php';
diff --git a/scripts/mail/mail_handler.php b/scripts/mail/mail_handler.php
--- a/scripts/mail/mail_handler.php
+++ b/scripts/mail/mail_handler.php
@@ -14,15 +14,7 @@
$root = dirname(dirname(dirname(__FILE__)));
require_once $root.'/scripts/__init_script__.php';
-require_once $root.'/externals/mimemailparser/Contracts/CharsetManager.php';
-require_once $root.'/externals/mimemailparser/Contracts/Middleware.php';
-require_once $root.'/externals/mimemailparser/Parser.php';
-require_once $root.'/externals/mimemailparser/Charset.php';
-require_once $root.'/externals/mimemailparser/Attachment.php';
-require_once $root.'/externals/mimemailparser/Exception.php';
-require_once $root.'/externals/mimemailparser/Middleware.php';
-require_once $root.'/externals/mimemailparser/MiddlewareStack.php';
-require_once $root.'/externals/mimemailparser/MimePart.php';
+require_once $root.'/externals/mimemailparser/__init.php';
$args = new PhutilArgumentParser($argv);
$args->parseStandardArguments();
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -3386,6 +3386,7 @@
'PhabricatorExternalAccountQuery' => 'applications/auth/query/PhabricatorExternalAccountQuery.php',
'PhabricatorExternalAccountsSettingsPanel' => 'applications/settings/panel/PhabricatorExternalAccountsSettingsPanel.php',
'PhabricatorExternalEditorSettingsPanel' => 'applications/settings/panel/PhabricatorExternalEditorSettingsPanel.php',
+ 'PhabricatorExternalMimeMailParserTestCase' => 'applications/metamta/externals/__tests__/PhabricatorExternalMimeMailParserTestCase.php',
'PhabricatorExtraConfigSetupCheck' => 'applications/config/check/PhabricatorExtraConfigSetupCheck.php',
'PhabricatorFacebookAuthProvider' => 'applications/auth/provider/PhabricatorFacebookAuthProvider.php',
'PhabricatorFact' => 'applications/fact/fact/PhabricatorFact.php',
@@ -9835,6 +9836,7 @@
'PhabricatorExternalAccountQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
'PhabricatorExternalAccountsSettingsPanel' => 'PhabricatorSettingsPanel',
'PhabricatorExternalEditorSettingsPanel' => 'PhabricatorEditEngineSettingsPanel',
+ 'PhabricatorExternalMimeMailParserTestCase' => 'PhabricatorTestCase',
'PhabricatorExtraConfigSetupCheck' => 'PhabricatorSetupCheck',
'PhabricatorFacebookAuthProvider' => 'PhabricatorOAuth2AuthProvider',
'PhabricatorFact' => 'Phobject',
diff --git a/src/applications/metamta/externals/__tests__/PhabricatorExternalMimeMailParserTestCase.php b/src/applications/metamta/externals/__tests__/PhabricatorExternalMimeMailParserTestCase.php
new file mode 100644
--- /dev/null
+++ b/src/applications/metamta/externals/__tests__/PhabricatorExternalMimeMailParserTestCase.php
@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * @phutil-external-symbol class \PhpMimeMailParser\Parser
+ */
+final class PhabricatorExternalMimeMailParserTestCase
+ extends PhabricatorTestCase {
+
+ /**
+ * Be sure to have mimemailparser classes.
+ */
+ private function initMimemailparser() {
+ // Not having this extension is probably a frequent error locally.
+ if (!function_exists('mailparse_msg_create')) {
+ $this->assertSkipped(pht('PHP mailparse extension is not installed'));
+ }
+
+ // Root of Phorge installation
+ $root = dirname(dirname(dirname(dirname(dirname(__DIR__)))));
+
+ // This is safe to be called multiple times.
+ require_once $root.'/externals/mimemailparser/__init.php';
+ }
+
+ public function testMailParse() {
+ $this->initMimemailparser();
+
+ $tests = array(
+ // Test case 0.
+ // Check that no silly "ISO" things are in the headers,
+ // even with esoteric accents.
+ __DIR__.'/data/test_accents',
+ );
+
+ foreach ($tests as $test) {
+ $test_file = $test.'.mbox';
+ $test_file_basename = basename($test_file);
+ $expected_headers_file = $test.'.headers.txt';
+
+ // Unpack the test.
+ $mail_content = Filesystem::readFile($test_file);
+ $expected_headers_raw = Filesystem::readFile($expected_headers_file);
+ $expected_headers = $this->readAssociativeConf($expected_headers_raw);
+
+ // Parse the email.
+ $parser = new \PhpMimeMailParser\Parser();
+ $parser->setText($mail_content);
+
+ // Check email fields headers from the corresponding txt file.
+ $headers = $parser->getHeaders();
+ foreach ($expected_headers as $k => $v) {
+ $this->assertEqual($v, $headers[$k], pht(
+ "Read the header '%s' from the test email %s",
+ $k,
+ $test_file_basename));
+ }
+
+ // If you are creative enough, you can do some tests on the body.
+// $content = array();
+// foreach (array('text', 'html') as $part) {
+// $part_body = $parser->getMessageBody($part);
+// $content[$part] = $part_body;
+// }
+ }
+ }
+
+ /**
+ * Get an associative array from "key:value" lines.
+ * @return array
+ */
+ private function readAssociativeConf(string $conf_raw) {
+ $conf = [];
+ $lines = explode("\n", $conf_raw);
+ foreach ($lines as $line) {
+ $line = trim($line);
+ if ($line !== '') {
+ list($k, $v) = explode(':', $line, 2);
+ $conf[$k] = $v;
+ }
+ }
+ return $conf;
+ }
+
+}
diff --git a/src/applications/metamta/externals/__tests__/data/test_accents.headers.txt b/src/applications/metamta/externals/__tests__/data/test_accents.headers.txt
new file mode 100644
--- /dev/null
+++ b/src/applications/metamta/externals/__tests__/data/test_accents.headers.txt
@@ -0,0 +1,3 @@
+from:Èxämplæ <myself-ääsdlääl@example.com>
+to:bossò-ääsdlääl@example.com
+subject:È ora di fare review! Aäällright
diff --git a/src/applications/metamta/externals/__tests__/data/test_accents.mbox b/src/applications/metamta/externals/__tests__/data/test_accents.mbox
new file mode 100644
--- /dev/null
+++ b/src/applications/metamta/externals/__tests__/data/test_accents.mbox
@@ -0,0 +1,39 @@
+From myself-ääsdlääl@example.com Tue Dec 3 15:07:14 2024
+Message-ID: <bb2f249a6e74b167d05b8c05977272c4fb78c0b7.camel@reyboz.it>
+Subject: =?ISO-8859-1?Q?=C8?= ora di fare review!
+ =?ISO-8859-1?Q?A=E4=E4llright?=
+From: =?ISO-8859-1?Q?=C8x=E4mpl=E6?= <myself-ääsdlääl@example.com>
+X-Evolution-Identity: df6e2e1cbb42dd3e8553007ad64b060e663ba7d0
+X-Evolution-Fcc: folder://88d77e0e58a4c694494b49c0910f14f16d180d17/Sent
+X-Evolution-Transport: 034c5b726f93fae6b9b88dfdee67e7a519e3ac39
+To: bossò-ääsdlääl@example.com
+X-Evolution-Draft-Folder:
+ folder://88d77e0e58a4c694494b49c0910f14f16d180d17/Drafts
+X-Evolution-Draft-Message: 1444
+X-Evolution-Format: text/html
+X-Evolution-Composer-Mode: text/plain
+Content-Type: multipart/alternative; boundary="=-ljePQpBKYtigz2UvrK3I"
+User-Agent: Evolution 3.46.4-2
+Date: Tue, 03 Dec 2024 15:07:14 +0100
+MIME-Version: 1.0
+X-Evolution-Source: 88d77e0e58a4c694494b49c0910f14f16d180d17
+
+--=-ljePQpBKYtigz2UvrK3I
+Content-Type: text/plain; charset="UTF-8"
+Content-Transfer-Encoding: 8bit
+
+Ottimo! È oraää di fare review. Bella zio.
+
+
+--=-ljePQpBKYtigz2UvrK3I
+Content-Type: text/html; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+<html x-evo-bgcolor="#1b1e20" x-evo-text="#fcfcfc" x-evo-link="#1d99f3" x-evo-vlink="#fcfcfc"><head x-evo-selection="anchorElem=[3] anchorOffset=0 anchorIsElement=1"><style id="x-evo-theme-sheet">html { background-color : #1b1e20; }
+html { color : #fcfcfc; }
+a { color : #1d99f3; }
+a:visited { color : #fcfcfc; }
+</style></head><body data-evo-draft=""><div style="width: 71ch;">Ottimo! È oraää di fare review. Bella zio.</div><div style="width: 71ch;"><span class="-x-evo-signature" id="none"></span></div><div style="width: 71ch;"><span class="-x-evo-signature" id="none"></span></div><div style="width: 71ch;"><br></div><div style="width: 71ch;" class="-x-evo-signature-wrapper"><span class="-x-evo-signature" id="none"></span></div></body></html>
+
+--=-ljePQpBKYtigz2UvrK3I--
+