In our development environment I redirect mails following some specific rules. I am quite sure that I achieved that in the past with
hook__civicrm_alterMailParams where I changed the
$params['toEmail'] to whatever email suited. Additionally I changed
$params['text']to have some info about the original email address.
Now this logic starts to fail after upgrading from CiviCRM 5.50.0 to 5.50.2 (when you send a mail to an individual contact from the contact view page). The reason is that
$params['toEmail] has now the value
NULL instead of a string with the email address. For sending mass mailings this logic still works - for every single email the hook is called with an $params array with 'toEmail' set.
The release notes from 5.50.1 and 5.50.2 did not show any code changes that seem to be related to that. How can I find someone to check that? It seems to be a main issue to me when changes like that are made in core without any information.