check for valid email address

rubyonrails-talk
1

Hi,

   I have one small question. I want to check for existence of email address. Means if user types "asfdsfsd@gmail.com", my model should throw an error to the user saying "email doesn't exist please check it once". How I can do this??

Thanks, Ramu

2

Do you have this user registered at your site with an email address?

There is no way to "test" a existing email with ex. google or other email hosts. (The smtp protocol allows for this but its a spam trap to have this available... )

You do have the ability to test if the domain exists and is a valid domain.. But again this can't be 100% because not all servers allow this inquiry and your connection to them might timeout

This would validate the domain (but could fail if you timeout.. ):

require 'resolv' def validate   unless errors.on(:email)     unless valid_domain?(email)       logger.debug "[DEBUG] - Domain name #{email} has a problem."       errors.add(:email, 'domain name appers to be incorrect')     end   end end

def valid_domain?(email)   domain = email.match(EMAIL_PATTERN)[2]   dns = Resolv::DNS.new   Timeout::timeout(SERVER_TIMEOUT) do

    # Check the MX record     mx_records = dns.getresources(domain, Resolv::DNS::Resource::IN::MX)

    mx_records.sort_by {|mx| mx.preference}.each do |mx|       a_records = dns.getresources(mx.exchange.to_s, Resolv::DNS::Resource::IN::A)       return true if a_records.any?     end

    #Try a straight A record    a_records = dns.getresources(domain, Resolv::DNS::Resource::IN::A)    a_records.any?    end rescue Timeout::Error, Errno::ECONNREFUSED   false end

Using a pattern is faster and just plain easier...

EMAIL_PATTERN = /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i validates_format_of :email, :with => EMAIL_PATTERN

3

Thank you very much! Any more ideas on how to validate the email address existence.

4

This doesn't exactly answer your question, but I think it may answer your concerns. Send an activation link of some sort to their email that they need to use to join your website.

That way, if it exists, then they get the email.

Ramon Tayag

5

What i have done is the followring (it is sort of a summary or a combination of what @freddy and @ramon said): first i check that the email is in correct format using this chunk of code:

# validate that password and confirm_password match, and that email is proper format   def validate_on_create     @email_format = Regexp.new(/^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,}) $/)     errors.add(:email, "must be a valid format") unless @email_format.match(email)     errors.add(:confirm_password, "does not match") unless password == confirm_password   end

which is in the user.rb file then in my controller i send an email to the user when they register with a link back to my controller with a hash at the end of it that is constructed through many ways (google tutorials on this, there are plenty) and my controller validates that the hash is correct and sets a boolean attribute of the user (call it email_confirmed if you will) to true. So the user can not log in to the site unless they have confirmed their email.

The other approach I have seen many site implement is to send the user their password to their email, which means they have to provide a valid email address to be able to log in. I am personally not very comfortable with sending a password through an email so I prefer to stay away from that method.

But again, these are not perfect methods, they're just a way to do what you want to get done. Maybe if OpenID picks up we won't have that problem anymore.