email address case sensitivity
Mailman Core deals with email addresses as case-insensitive (e.g. nobody@somewhere.org), but keeps "original" email addresses (e.g. Nobody@somewhere.org) to be used when emails are sent by users: Case-preserved-addresses
It looks that when Mailman Core API is used to get email addresses associated with a list, it returns not case-preserved addresses. AFAIK, this has two issues:
First, this is a bug when these addresses are compared with case-preserved ones from another "source" like in case of user_is_in_list_roster() in src/postorius/auth/utils.py. I have hitted that when an email address of an owner of a list is case-sensitive. Then, the owner is not recognized as the email addresses did not match. I have hacked it by making the addresses from EmailAddress.objects lower-case in that function for now.
Second, it has an unwelcome consenquence when the email addresses associated with a list are shown on a web page, always all in lower-case. That may be unexpected and looks suspicious. Exemplary example is when a new owner is being added to a list, its email address is case-sensitive, but after hitting the add button, the address shown in the list is in lower-case.
IMO, the comparision of email addresses in user_is_in_list_roster() should be fixed to deal with email addresses different in case, as for sake of sanity, they must be equivalent. Futher, it's a question if Mailman Core API should supply even case-preserved email address in some calls.