Email address with non-ASCII character causes delivery error
I know that e-mailadresses with "ß" are invalid in general, but you can enter them in redmine. That causes that any notification to a ticket which are related to the person with the "ß" mail couldnt be send.
The "to:" mailadress in the maillog is something like "to=<=?UTF-8?B?bWFyY2VsLnBsYcOfQGJ1cmctZ21iaC5kZQ==?=>" for everyone who is related.
-> No one will be notified.