[DRE-maint] Bug#1068334: schleuder: receive_from_subscribed_emailaddresses_only(): is case-sensitive wrt email addresses, and thus might erroneously reject mails

[Georg Faerber]

Package: schleuder
Version: 4.0.3-7
Forwarded: https://0xacab.org/schleuder/schleuder/-/issues/476
Tags: bookworm fixed-upstream upstream

Both schleuder-cli and schleuder-web nowadays enforce lowercase if
adding subscriptions. Thus, valid emails might get rejected, if an
uppercase email address is used in the From: header.