I've noticed that there are a lot of users that misspell their email addresses when registering. For example, if the email is example@gmail.com, the user may write example@gmail.con. In a registering process, this may lead to the user registering wrong without him/her being aware of.
Is it a good idea to implement a function that changes .con for .com? This would be a problem if .con email addresses exist because they wouldn't be able to register. Do .con email addresses exist?
.con emails cannot exist (right now) because there is not a top-level domain (TLD) named .con
If you go to the Wikipedia page or tld-list.com, you'll see that there isn't a .con
No .con to be found.
You should probably popup a warning instead of automatically fixing it, though, so that clients are conscious that they made a mistake.