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
@@ -12668,7 +12668,7 @@
     'PhutilRemarkupDelRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupDocumentLinkRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupEngine' => 'PhutilMarkupEngine',
-    'PhutilRemarkupEngineTestCase' => 'PhutilTestCase',
+    'PhutilRemarkupEngineTestCase' => 'PhabricatorTestCase',
     'PhutilRemarkupEscapeRemarkupRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupEvalRule' => 'PhutilRemarkupRule',
     'PhutilRemarkupHeaderBlockRule' => 'PhutilRemarkupBlockRule',
diff --git a/src/infrastructure/env/PhabricatorEnv.php b/src/infrastructure/env/PhabricatorEnv.php
--- a/src/infrastructure/env/PhabricatorEnv.php
+++ b/src/infrastructure/env/PhabricatorEnv.php
@@ -11,7 +11,7 @@
  * The primary role of this class is to provide an API for reading
  * Phabricator configuration, @{method:getEnvConfig}:
  *
- *   $value = PhabricatorEnv::getEnvConfig('some.key', $default);
+ *   $value = PhabricatorEnv::getEnvConfig('some.key');
  *
  * The class also handles some URI construction based on configuration, via
  * the methods @{method:getURI}, @{method:getProductionURI},
@@ -428,14 +428,28 @@
   }
 
 
+  /**
+   * Check whenever an URI points to this very same Phorge installation.
+   * @param string $raw_uri
+   * @return bool True, if this URI points to Phorge itself.
+   */
   public static function isSelfURI($raw_uri) {
     $uri = new PhutilURI($raw_uri);
 
+    // Relative paths always are self-URIs.
     $host = $uri->getDomain();
-    if (!phutil_nonempty_string($host)) {
+    $prot = $uri->getProtocol();
+    $empty_host = !phutil_nonempty_string($host);
+    $empty_prot = !phutil_nonempty_string($prot);
+    if ($empty_host && $empty_prot) {
       return true;
     }
 
+    // Probably this is a mailto.
+    if ($empty_host) {
+      return false;
+    }
+
     $host = phutil_utf8_strtolower($host);
 
     $self_map = self::getSelfURIMap();
diff --git a/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php b/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
--- a/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
+++ b/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
@@ -2,10 +2,12 @@
 
 /**
  * Test cases for @{class:PhutilRemarkupEngine}.
+ * This needs to be a PhabricatorTestCase since it may want
+ * to access some Phorge URI configurations.
  * @TODO: This unit is not always triggered when you need it.
  *        https://we.phorge.it/T15500
  */
-final class PhutilRemarkupEngineTestCase extends PhutilTestCase {
+final class PhutilRemarkupEngineTestCase extends PhabricatorTestCase {
 
   public function testEngine() {
     $root = dirname(__FILE__).'/remarkup/';
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
@@ -1,5 +1,5 @@
 <http://www.zany.com/omg/weird_url,,,>
 ~~~~~~~~~~
-<p><a href="http://www.zany.com/omg/weird_url,,," class="remarkup-link" target="_blank" rel="noreferrer">http://www.zany.com/omg/weird_url,,,</a></p>
+<p><a href="http://www.zany.com/omg/weird_url,,," class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.zany.com/omg/weird_url,,,</a></p>
 ~~~~~~~~~~
 http://www.zany.com/omg/weird_url,,,
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
@@ -10,17 +10,17 @@
 
 Quick! http://www.example.com/!
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p>(<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
+<p>(<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/wiki/example_(disambiguation)" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/wiki/example_(disambiguation)</a></p>
+<p><a href="http://www.example.com/wiki/example_(disambiguation)" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/wiki/example_(disambiguation)</a></p>
 
-<p>(example <a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
+<p>(example <a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
 
-<p>Quick! <a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>!</p>
+<p>Quick! <a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>!</p>
 ~~~~~~~~~~
 http://www.example.com/
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mailto.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mailto.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mailto.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mailto.txt
@@ -5,11 +5,11 @@
 [[mailto:alincoln@example.com]]
 
 ~~~~~~~~~~
-<p><a href="mailto:alincoln@example.com" class="remarkup-link" target="_blank" rel="noreferrer">mail me</a></p>
+<p><a href="mailto:alincoln@example.com" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">mail me</a></p>
 
-<p><a href="mailto:alincoln@example.com" class="remarkup-link" target="_blank" rel="noreferrer">mail me</a></p>
+<p><a href="mailto:alincoln@example.com" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">mail me</a></p>
 
-<p><a href="mailto:alincoln@example.com" class="remarkup-link" target="_blank" rel="noreferrer">alincoln@example.com</a></p>
+<p><a href="mailto:alincoln@example.com" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">alincoln@example.com</a></p>
 ~~~~~~~~~~
 mail me <alincoln@example.com>
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
@@ -5,11 +5,11 @@
 <http://www.example.com/ [[http://www.example.net/ | Example]]>
 
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a>(<a href="http://www.alternate.org/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)</p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a>(<a href="http://www.alternate.org/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)</p>
 
-<p>(<a href="http://www.alternate.org/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a></p>
+<p>(<a href="http://www.alternate.org/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a></p>
 
-<p>&lt;<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a> <a href="http://www.example.net/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a>&gt;</p>
+<p>&lt;<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a> <a href="http://www.example.net/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a>&gt;</p>
 ~~~~~~~~~~
 Example <http://www.example.com/>(http://www.alternate.org/)
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-noreferrer.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-noreferrer.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-noreferrer.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-noreferrer.txt
@@ -1,15 +1,27 @@
+I have no idea what should happen in this case.
+Technically it does not seem to be an external link.
+Browsers may make it external, though?
+But I guess that the TARGET attribute is not the important part here...
+
 [[ /\evil.com ]]
 
 [[ /
 /evil.com ]]
 
 ~~~~~~~~~~
-<p><a href="/\evil.com" class="remarkup-link" target="_blank" rel="noreferrer">/\evil.com</a></p>
+<p>I have no idea what should happen in this case.
+Technically it does not seem to be an external link.
+Browsers may make it external, though?
+But I guess that the TARGET attribute is not the important part here...</p>
+
+<p><a href="/\evil.com" class="remarkup-link" rel="noreferrer">/\evil.com</a></p>
 
 <p><a href="/
-/evil.com" class="remarkup-link" target="_blank" rel="noreferrer">/
+/evil.com" class="remarkup-link" rel="noreferrer">/
 /evil.com</a></p>
 ~~~~~~~~~~
+I have no idea what should happen in this case. Technically it does not seem to be an external link. Browsers may make it external, though? But I guess that the TARGET attribute is not the important part here...
+
 /\evil.com
 
 /
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
@@ -2,9 +2,9 @@
 
 http://www.example.com/
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" rel="noreferrer">http://www.example.com/</a></p>
 ~~~~~~~~~~
 http://www.example.com/
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
@@ -8,11 +8,11 @@
 
 [[#anchor | Anchors ]]
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">example.com</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">example.com</a></p>
 
-<p><a href="http://www.example.com/x/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/x/</a></p>
+<p><a href="http://www.example.com/x/" class="remarkup-link" rel="noreferrer">http://www.example.com/x/</a></p>
 
 <p><a href="http://www.example.com/page/#anchor" class="remarkup-link" rel="noreferrer">http://www.example.com/page/#anchor</a></p>
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-tel.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-tel.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-tel.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-tel.txt
@@ -5,11 +5,11 @@
 [[tel:18005555555]]
 
 ~~~~~~~~~~
-<p><a href="tel:18005555555" class="remarkup-link" target="_blank" rel="noreferrer">call me</a></p>
+<p><a href="tel:18005555555" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">call me</a></p>
 
-<p><a href="tel:18005555555" class="remarkup-link" target="_blank" rel="noreferrer">call me</a></p>
+<p><a href="tel:18005555555" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">call me</a></p>
 
-<p><a href="tel:18005555555" class="remarkup-link" target="_blank" rel="noreferrer">18005555555</a></p>
+<p><a href="tel:18005555555" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">18005555555</a></p>
 ~~~~~~~~~~
 call me <18005555555>
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
@@ -2,8 +2,8 @@
 http://www.example.com/..
 http://www.example.com/!!!
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>,
-<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>..
-<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>!!!</p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>,
+<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>..
+<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>!!!</p>
 ~~~~~~~~~~
 http://www.example.com/, http://www.example.com/.. http://www.example.com/!!!
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
@@ -1,5 +1,5 @@
 http://www.example.com/~~
 ~~~~~~~~~~
-<p><a href="http://www.example.com/~" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/~</a></p>
+<p><a href="http://www.example.com/~" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/~</a></p>
 ~~~~~~~~~~
 http://www.example.com/~~
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link.txt
@@ -1,5 +1,5 @@
 http://www.example.com/
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 ~~~~~~~~~~
 http://www.example.com/
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/percent-block-multiline.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/percent-block-multiline.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/percent-block-multiline.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/percent-block-multiline.txt
@@ -10,7 +10,7 @@
 <br />- second
 <br />- third</p>
 
-<p><a href="http://hello" class="remarkup-link" target="_blank" rel="noreferrer">world</a></p>
+<p><a href="http://hello" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">world</a></p>
 ~~~~~~~~~~
 **foo**
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/simple-table-with-link.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/simple-table-with-link.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/simple-table-with-link.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/simple-table-with-link.txt
@@ -1,7 +1,7 @@
 | [[ http://example.com | name ]] | [x] |
 ~~~~~~~~~~
 <div class="remarkup-table-wrap"><table class="remarkup-table">
-<tr><td><a href="http://example.com" class="remarkup-link" target="_blank" rel="noreferrer">name</a></td><td>[x]</td></tr>
+<tr><td><a href="http://example.com" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">name</a></td><td>[x]</td></tr>
 </table></div>
 ~~~~~~~~~~
 | name <http://example.com> | [x] |
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/toc.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/toc.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/toc.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/toc.txt
@@ -13,11 +13,11 @@
 <li><a href="#http-www-example-com">http://www.example.com</a></li>
 </ul>
 
-<h2 class="remarkup-header"><a name="link-name"></a><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">link_name</a></h2>
+<h2 class="remarkup-header"><a name="link-name"></a><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">link_name</a></h2>
 
 <h3 class="remarkup-header"><a name="bold"></a><strong>bold</strong></h3>
 
-<h2 class="remarkup-header"><a name="http-www-example-com"></a><a href="http://www.example.com" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com</a></h2>
+<h2 class="remarkup-header"><a name="http-www-example-com"></a><a href="http://www.example.com" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com</a></h2>
 ~~~~~~~~~~
 [[ http://www.example.com/ | link_name ]]
 =========================================
diff --git a/src/infrastructure/parser/__tests__/PhutilURIHelperTestCase.php b/src/infrastructure/parser/__tests__/PhutilURIHelperTestCase.php
--- a/src/infrastructure/parser/__tests__/PhutilURIHelperTestCase.php
+++ b/src/infrastructure/parser/__tests__/PhutilURIHelperTestCase.php
@@ -4,6 +4,12 @@
 
  public function testPhutilURIHelper() {
 
+    // Set a test environment.
+    // This is useful to don't rely on your local config.
+    $base = 'https://phorge.localhost';
+    $env = PhabricatorEnv::beginScopedEnv();
+    $env->overrideEnvConfig('phabricator.base-uri', $base);
+
     // Every row is a test. Every column is:
     // - 0: name of the test
     // - 1: test input value
@@ -20,16 +26,14 @@
       array('internal root dir', '/#asd', true, false, true),
       array('external', 'https://gnu.org/', false, false, false),
       array('external anchor', 'https://gnu.org/#asd', false, false, false),
+      array('mail', 'mailto:info@wikipedia.org', false, false, false),
+      array('tel', 'tel:+555555555', false, false, false),
+      array('alien protocol', 'foo://whatever', false, false, false),
+      array('base uri', $base, true, false, false),
+      array('base uri anchor', "{$base}#asd", true, false, false),
+      array('base uri path', "$base/something", true, false, false),
     );
 
-    // Add additional self-tests if base URI is available.
-    $base = PhabricatorEnv::getEnvConfigIfExists('phabricator.base-uri');
-    if ($base) {
-      $domain = id(new PhutilURI($base))->getDomain();
-      $tests[] = array('base uri', $base, true, false, false);
-      $tests[] = array('base uri anchor', "{$base}#asd", true, false, false);
-    }
-
     foreach ($tests as $test) {
       $name = $test[0];
       $uri = $test[1];