User email address should not be overwritten by invalid/empty value

[prondzyn]

The application should keep user's emails in internal database and not update them with invalid/empty value provided in further RSVPs.

Consider scenario:

1. During RSVP to Meetup 23 user John Doe has provided valid email "[email protected]"
   • user John Doe will take part in giveaway's draw
2. During RSVP to Meetup 24 user John Doe has forgotten provide an email
   • even though user John Doe has forgotten provide an email this time, he should take part in giveaway's draw because we can get his email from our database

The application should also follow below scenario:

1. During RSVP to Meetup 23 user John Doe has provided valid email "[email protected]"
   • user John Doe will take part in giveaway's draw
2. During RSVP to Meetup 24 user John Doe has provided valid email "[email protected]"
   • user John Doe will take part in giveaway's draw but with the new email

[sawickil]

I'm not sure about this one. To keep it simple and clear I would just take the current email from Meetup. If there was no email or was an incorrect one, I wouldn't use any email for that person.