We have the custom cookie integration and set the email address in the cookie from our own website.
When you write an email address into a cookie it will encode the non-web symbols. The @ symbol becomes %40.
(example : myname@xyz.com becomes myname%40xyz.com)
When a user loges into the community server site , it is updating their email address with the %40 in the cs_users email address table. ie. Table values becomes myname%40xyz.com.
Not sure why cs login process is updating the email address field. How to get rid if this ?