I have a web app at which visitors are signing up and getting a newsletter to the email they registered with.
I am using only a single email field in the signup form, since I wish to reduce the number of fields plus I figure most people (like me) copy and paste the email which mean a typo would propagate to the secondary verification field.
My problem is that a fair percentage of the signups have a typo in the email address, e.g. @yhaoo, @hotmaill, etc.
How can I effectively deal with such typos?
I was thinking of doing a simple auto-correction by using a list of misspellings for common domains, but I can’t a ready-made comprehensive list for that.
First, you should first make a DNS lookup to see if there’s a valid MX record for that domain (which implies the domain should exist) – if not you shouldn’t accept that email.
Second, look for an http redirect from the domain to another domain. E.g. yayoo.com and yahooo.com both redirect to yahoo.com, so you may want to show a warning message “Did you mean …@yahoo.com ?” or even automatically correct the addresses from a whitelist that you’ve made sure are safe to correct.
Lastly, if there’s a valid MX record and no redirect, your remaining culprits will most likely be just typos that lead to hitfarms riding on typos for large providers (or innocent other services) e.g. gmial.com. For these you can resort to manually building a hash table of auto-correct suggestions (again, offering the user a “Did you mean..” step before accepting the submission.