Version: OpenEMM 2011 on Linux
Create a CSV file with any delimiters that contain any columns, and specify this URL as the email field.
Then upload, and click "Start Import". OpenEMM compalins about a "General Error".
For most URLs, the importer correctly notes the field as incorrect and allows correction or ignore. Only for the URL above, the general error happens. Reporting because it was a blocker for the non-techie user it happened to.