Important: #101776 - Email validation in GeneralUtility::validEmail() now rejects spaces before "@"

See forge#101776

Description

The GeneralUtility::validEmail() method uses the package egulias/email-validator for validating emails. This library treats an email address like email @example.com with a space before the @ character as valid, but issues a warning, which has previously not been caught by TYPO3. Warnings like these are defined as "deviations from the RFC that in a broader interpretation are accepted."

In the context of TYPO3, such non-RFC email address shall be rejected. Thus, this specific warning (CFWSNearAt) will now be caught, and the warning is turned into an invalidation of the given email address.

This will have the effect, that if integrators previously accepted email addresses formatted like these, validation will now fail (as the RFC implies).