CRM-21768_NOFOLLOW_links_in_public_online_view_of_mailings

[eileenmcnaughton]

Overview

Replaces #11673 with test fix

This patch makes sure the trackable url links in the public view of mailings get the nofollow tag so Google will not index urls with a syntax like: https://abc.xyz/sites/all/modules/civicrm/extern/url.php?u=1234&qid=4321

Before

Currently Google (and possibly other search engines) index the trackable urls, so url's like:
https://abc.xyz/sites/all/modules/civicrm/extern/url.php?u=1234&qid=4321
end up in the search index.

After

Trackable urls get the tag rel='NOFOLLOW', which means Google will not follow the links, which could only happen in a situation of a public viewable mailing anyway. The mailing itself is still able to get indexed. Note: this does not 100% prevent Google from indexing, others means like robots.txt are more robust for that. But this patch at least prevents the strange indexed urls for default configurations.

Technical Details

adding rel='NOFOLLOW' to trackable urls to TrackableURL.php does the trick so far.

Comments

(Another option would have been to insert a metatag in the head of CRM/Mailing/Page/View.php)

[civibot]

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[eileenmcnaughton]

Adding merge on pass per original PR