diff --git a/addons/link_tracker/models/mail_render_mixin.py b/addons/link_tracker/models/mail_render_mixin.py
index f7ff2d4548b..dcb0f4ccd18 100644
--- a/addons/link_tracker/models/mail_render_mixin.py
+++ b/addons/link_tracker/models/mail_render_mixin.py
@@ -38,6 +38,9 @@ class MailRenderMixin(models.AbstractModel):
         short_schema = base_url + '/r/'
         for match in set(re.findall(tools.HTML_TAG_URL_REGEX, html)):
             long_url = match[1]
+            # Make relative links absolute
+            if long_url.startswith(('/', '?', '#')):
+                long_url = base_url + long_url
             # Don't shorten already-shortened links
             if long_url.startswith(short_schema):
                 continue
@@ -50,7 +53,7 @@ class MailRenderMixin(models.AbstractModel):
             link = self.env['link.tracker'].search_or_create(create_vals)
             if link.short_url:
                 # `str` manipulation required to support replacing "&" characters, common in urls
-                new_href = match[0].replace(long_url, link.short_url)
+                new_href = match[0].replace(match[1], link.short_url)
                 html = html.replace(markupsafe.Markup(match[0]), markupsafe.Markup(new_href))
 
         return html
diff --git a/addons/link_tracker/tests/test_mail_render_mixin.py b/addons/link_tracker/tests/test_mail_render_mixin.py
index b008fe75eca..c60198daf23 100644
--- a/addons/link_tracker/tests/test_mail_render_mixin.py
+++ b/addons/link_tracker/tests/test_mail_render_mixin.py
@@ -30,6 +30,7 @@ class TestMailRenderMixin(common.HttpCase):
             """,
             '<a href="https://test_escaped.com" title="title" fake="fake"> test_escaped &lt; &gt; </a>',
             '<a href="https://url_with_params.com?a=b&c=d">label</a>',
+            '<a href="#"></a>',
         ]
 
         self.env["mail.render.mixin"]._shorten_links("".join(test_links), {})
@@ -49,6 +50,7 @@ class TestMailRenderMixin(common.HttpCase):
                 ("url", "=", "https://url_with_params.com?a=b&c=d"),
                 ("label", "=", "label"),
             ],
+            [("url", "=", self.base_url + '#')],
         ]
         trackers_to_fail = [
             [("url", "=", "https://test_542152qsdqsd.com"), ("label", "ilike", "_")]
@@ -86,6 +88,7 @@ class TestMailRenderMixin(common.HttpCase):
             'And a third: <a href="{base_url}">Here</a>\n'
             'And a forth: <a href="{base_url}">Here</a>\n'
             'And a fifth: <a href="{base_url}">Here too</a>\n'
+            'And a 6th: <a href="/web">Here</a><br>\n'
             'And a last, more complex: <a href="https://boinc.berkeley.edu/forum_thread.php?id=14544&postid=106833">There!</a>'
             .format(base_url=self.base_url)
         )
@@ -95,6 +98,7 @@ class TestMailRenderMixin(common.HttpCase):
             'And a third: <a href="{base_url}/r/([\\w]+)">Here</a>\n'
             'And a forth: <a href="{base_url}/r/([\\w]+)">Here</a>\n'
             'And a fifth: <a href="{base_url}/r/([\\w]+)">Here too</a>\n'
+            'And a 6th: <a href="{base_url}/r/([\\w]+)">Here</a><br>\n'
             'And a last, more complex: <a href="{base_url}/r/([\\w]+)">There!</a>'
             .format(base_url=self.base_url)
         )