Code review comment for lp:~black-perl/mailman/fix-mailman

What this means is that people cannot subscribe two email addresses to a mailing list that differ only in case. In some sense this conflicts with the model, since the case-different email addresses are considered different address objects, but I still think given the stated policy of case-preserving case-insensitive addresses, this will be acceptable.

It will still probably be possible to link two addresses to the user which differ only in case, but since these can't both be subscribed to the same mailing list (with the same role), I suppose we'll have to accept this oddity.

It's also possible to subscribe a user with a preferred address that differs in case with another address object linked to the user. This is consistent with the existing semantics.