I have an instance of Phabricator running, and have it setup to only allow registration from a particular domain. It is also setup with LDAP so the email addresses come back automatically. The problem is that for some reason a few accounts were setup with "FictitiousDomain.com" instead of "fictitiousdomain.com".
auth.email-domains is "fictitiousdomain.com" and any users that have different casing there are being denied.
I noticed that some older release notifications mentioned case-insensitive email. Maybe this area was missed?