Site full name with & is not processed properly in any email subject. As an example, the new user email will contain the site name as the subject and if the site name includes &, it will process the '&' as '&'
Example:
Site full name - Electronics '&' spare parts
Email subject while sending the email: Electronics '&' spare parts
P.S. '' and space used to get rid of HTML issue while posting.First image: The full site name
Second image: Actual Email