I have q2a setup that guests can ask questions without registration.
The main problem: When they add their email address in the last field for notification, many of them state wrong emails. This results in many incoming emails "Mail Delivery Failed" in my email account.
Another problem: What if someone adds an email address of a complete different person.
Solution approach 1: Only allow registered users (with email confirmed) to ask. But this would limit the number of incoming questions.
Solution approach 2: Send an email to the email given and ask for confirmation. ← This approach seems good enough.
I would also suggest to store this email as valid email later on so it does not need to be validated again.