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bramu.ss-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2008-Oct-11 19:22 UTC

check for valid email address

Hi,

   I have one small question. I want to check for existence of email
address. Means if user types
"asfdsfsd-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org", 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
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Freddy Andersen

2008-Oct-11 19:38 UTC

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Re: check for valid email address

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
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bramu.ss-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

2008-Oct-11 20:22 UTC

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Re: check for valid email address

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

On Oct 12, 12:38 am, Freddy Andersen
<fre...-RCI/mp9mI1I6GGFevw1D/A@public.gmane.org>
wrote:> 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--~--~---------~--~----~------------~-------~--~----~
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Ramon Miguel M. Tayag

2008-Oct-11 20:35 UTC

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Re: check for valid email address

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



On Sun, Oct 12, 2008 at 4:22 AM,
bramu.ss-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<bramu.ss-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:>
> Thank you very much! Any more ideas on how to validate the email
> address existence.
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Youssef Chaker

2008-Oct-12 03:44 UTC

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Re: check for valid email address

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.

On Oct 11, 3:22 pm, "bramu...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org"
<bramu...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Hi,
>
>    I have one small question. I want to check for existence of email
> address. Means if user types
"asfds...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org", 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--~--~---------~--~----~------------~-------~--~----~
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Rails - Oct 2008 - check for valid email address

check for valid email address

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