PC with only characters like ! . , results in "403 Forbidden" erorr
example url http://www.domain.com/conversations/.1234/unread
from error.log
[error] 53402#0: *1791175 access forbidden by rule, client: x.x.x.x., server: www.domain.com, request: "GET /conversations/.1234/unread HTTP/1.1"...