View source for MediaWiki:Spam-whitelist

 #<!-- leave this line exactly as it is --> <pre>
# External URLs matching this list will *not* be blocked even if they would
# have been blocked by blacklist entries.
#
# Syntax is as follows:
#   * Everything from a "#" character to the end of the line is a comment
#   * Every non-blank line is a regex fragment which will only match hosts inside URLs

t\.co
youtu\.be

 #</pre> <!-- leave this line exactly as it is -->