Synnefo

When adding multiple users to a project via a comma-separated email list
in the corresponding form, if any of the emails does not validate,
then none of them is processed and added to the project.

This makes it very time-consuming to add a large number of members, as
weeding out the invalid emails must be done in repeated trial-and-error attempts.

The system should always identify the invalid emails,
and then ask the user to confirm the processing of the rest
(or don't ask, but the identification of the invalid must be done,
or else the user will never know something/what was wrong with
their list)