fix: unescape in URLs which are stored for tracking

closes #2568
closes #907
closes #115

lib/postal/message_parser.rb

@@ -118,7 +118,8 @@ module Postal
         part.gsub!(/href=(['"])(#{URL_REGEX})['"]/) do
           if track_domain?($~[:domain])
             @tracked_links += 1
-            token = @message.create_link($~[:url])
+            url = CGI.unescapeHTML($~[:url])
+            token = @message.create_link(url)
             "href='#{domain}/#{@message.server.token}/#{token}'"
           else
             ::Regexp.last_match(0)

script/send_html_email.rb

@@ -36,7 +36,7 @@ mail.html_part = Mail::Part.new do
     <p>Hello there</p>
     <p>This is an example email. It doesn't do all that much.</p>
     <p>Some other characters: őúéáűí</p>
-    <p>There is a <a href='https://postalserver.io/test-plain-text-link?foo=bar&baz=qux'>link here</a> though...</p>
+    <p>There is a <a href='https://postalserver.io/test-plain-text-link?foo=bar&amp;baz=qux'>link here</a> though...</p>
   BODY
 end