"Email - full quote: yes" and a link in the signature lead to exponential article growth

[martin.von.wittich]

Infos:

• Used Zammad version: 2.9.x
• Used Zammad installation source: docker-compose
• Operating system: Debian 9
• Browser + version: Chrome 74

Expected behavior:

• Enabling “Email - full quote” and putting a HTML link (e.g. http://example.com) in the signature should not lead to exponential ticket growth when replying multiple times with a customer back and forth.

Actual behavior:

• When replying, Zammad will add a “link target footnote” to the plain-text part of the reply for each link in the reply. Ie. if your signature contains the text “website: example.com”, the plain text part will look like this:

  website: [1] example.com
  
  [1] http://example.com
  

• When the customer replies to the plain-text part of Zammad’s reply with full quote in his email client enabled, both URLs will end up in the fullquote.

• When the agent views the customer’s response, Zammad will linkify both URLs in the fullquote, ie. to the agent, the fullquote will now look like this:

  website: [1] example.com

  [1] http://example.com

• When the agent now replies, the mail will contain three links:

  1. the “website: example.com” in the signature
  2. the “website: [1] example.com” in the fullquote
  3. the “[1] http://example.com” in the fullquote

  Zammad will now add three new “link target footnotes” that will look like this:

  [1] http://example.com
  [2] http://example.com
  [3] http://example.com
  

• Each back-and-forth reply with a customer doubles the amount of “link target footnotes”

  In extreme cases (after ~9 agent replies), this will prevent the agent from answering the ticket because there are >1000 links in the ticket and the reply is too long. Zammad will simply prevent the agent from typing anything in the response text box.

Steps to reproduce the behavior:

• Add a link to your Zammad signature. Ensure that the link is a HTML link. You can’t manually input a link into Zammad, but you can easily copy-paste it; just copy-paste the URL of your Zammad instance from the browser’s address bar into the signature. You can tell it’s really a link when it has the typical blue link color.

• Send a test mail to an external mail address.

• Open the mail in the external mail client. Ensure that the mail client will quote the plain-text part of the mail. You can tell that this is the case when you click on reply and it says > [1] http://example.com/ at the very bottom of the reply. Send the reply.

• Reply again in Zammad.

• Either view the last reply in the external mail client, or click on your last reply to expand the detail view and click on “Raw” (you won’t see the problem in Zammad’s article view yet as the “link target footnotes” only get added to the plain-text part of the response, and Zammad displays the HTML part).

• Note that the plain-text part of your last reply contains three “link target footnotes”:

  [1] http://example.com
  [2] http://example.com
  [3] http://example.com
  

• Rinse and repeat to get a lot of “link target footnotes”.

Pretty certain that this is a bug, but I thought I’d better post in the community first