Thunderbird: 31.7.0
Sogo Connector: 24.0.2 ( interesstingly, no updates shown)
Lightning: 3.3.3
It looks like the "@" is misintrepreted as the @ from such an url:
"http://user:password@domain/...." which it isn't, as it's clearly in the URI part.
Actual results:
TB ( or Lightning or Sogo ) does not even try to connect to the server.
Expected results:
TB ( or Lightning or Sogo ) should work normally, as the same CalDAV url with an @ in the username works as expected. | 
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