I'd like to propose in a TIP the dropping of the email unique constraint.
Why ?
It was a bad idea in the first place. E-mails are not unique, regardless how much we would like this to be. Take "mailto:info@bmw.org";. A couple of people would respond to this email. And would use this email when communicating with others (irrespectable of their actual email).
Where did it come from?
Originally we were supposed to log into the system using our e-mail. For this the e-mail needed to be unique. But it doesn't need to be unique anymore. We can login with a user name that just has to be unique on our site. Furthermore, this will allow us to have a real CRM system, which takes into account that e-mails can be used multiple times (we can't at the moment because storing the email in an Attribute would work, but then all the benefits of having an e-mail associated with a party are gone...).
What is the drawback ?
You would have to drop the option to register via e-mail. As the username is set to the email address anyway by default, this should be a no issue on upgrades and definitely on new sites. But maybe I'm wrong.
Does cognovis need it?
Not really. We just drop the parties_email_un constraint in all out custom packages, but I refrain from dropping it in contacts where it should be as I'm not entirely sure if this would require a TIP as well (sneaking in core changes through the backdoor).
And the last answer is the reason why I did not go for a full fledged TIP. I would like to get some feedback first before proposing it as a change for 5.3.
What does the community think about changing this fundamental part of the core?