email addresses with german umlauts (and I'm sure also for all other non-ascii characters) like test@müller.de are not validated correctly.
The result of isValid("email","test@müller.de") is false but should be true.
When using this address in cfmail like
<cfmail from="..." to="test@müller.de" ...>
results in an error saying
One of the following attribtues must be defined (to, cc, bcc)
a workaround is converting the email address to punycode manually:
But this should be done automatically by Lucee. The developer exception is, that email addresses like this are recognized as valid addresses, because they are.
This is really a blocker, because it means, that all applications validating these addresses fail with emails with non-ascii characters!
I've confirmed the issue happened on latest version of lucee 188.8.131.52. In lucee cfmail "to" attribute has a value non-ascii characters it throw error like "One of the following attribtues must be defined [ to, cc, bcc ]". In ACF also doesn't accepts non-Ascii character it throws error like "The value of the attribute to, which is currently test@mÃ¼ller.de, is invalid." will confirm about the issue.