Rails - Jun 2005 - Email domain validation - Net::SMTPFatalError

The last step of my email validation looks like this:

begin
	Mailer::deliver_complete(@user)
rescue Net::SMTPFatalError
	@user.errors.add "email", "There was a problem with the
verification
of your email. Please check and try again."
end

It works great if the user puts in an invalid user with a valid domain, 
throwing the error as expected. However with an invalid domain, somehow 
it passes. How do I check to make sure that the email actually went 
through?
___________________
Ben Jackson
Diretor de Desenvolvimento

ben-p14LI7ZcAE/pVLaUnt/cCQC/G2K4zDHf@public.gmane.org
http://www.incomumdesign.com

I never saw an answer to this post. Anyone have an idea what I can do 
to verify that an email _really_ works?

Ben

On Jun 14, 2005, at 8:12 PM, Ben Jackson wrote:
> The last step of my email validation looks like this:
>
> begin
> 	Mailer::deliver_complete(@user)
> rescue Net::SMTPFatalError
> 	@user.errors.add "email", "There was a problem with the
verification
> of your email. Please check and try again."
> end
>
> It works great if the user puts in an invalid user with a valid 
> domain, throwing the error as expected. However with an invalid 
> domain, somehow it passes. How do I check to make sure that the email 
> actually went through?
> ___________________
> Ben Jackson
> Diretor de Desenvolvimento
>
> ben-p14LI7ZcAE/pVLaUnt/cCQC/G2K4zDHf@public.gmane.org
> http://www.incomumdesign.com
>
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

I guess it''s practically impossible. The SMTP server can have a lot of 
reasons to reject en e-mail adress. I''m currently working on a 
"newsletter-mailing-application", we parse all e-mail addresses with 
TMail (to make sure all adresses are according to RFC) but there is no 
practical way (unless you want to do DNS queries etc) to check if an 
e-mail address realy works.

Flurin

Ben Jackson wrote:
> I never saw an answer to this post. Anyone have an idea what I can do 
> to verify that an email _really_ works?
>
> Ben
>
> On Jun 14, 2005, at 8:12 PM, Ben Jackson wrote:
>
>> The last step of my email validation looks like this:
>>
>> begin
>>     Mailer::deliver_complete(@user)
>> rescue Net::SMTPFatalError
>>     @user.errors.add "email", "There was a problem with
the
>> verification of your email. Please check and try again."
>> end
>>
>> It works great if the user puts in an invalid user with a valid 
>> domain, throwing the error as expected. However with an invalid 
>> domain, somehow it passes. How do I check to make sure that the email 
>> actually went through?
>> ___________________
>> Ben Jackson
>> Diretor de Desenvolvimento
>>
>> ben-p14LI7ZcAE/pVLaUnt/cCQC/G2K4zDHf@public.gmane.org
>> http://www.incomumdesign.com
>>
>> _______________________________________________
>> Rails mailing list
>> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>>
>
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

On Jun 28, 2005, at 2:25 PM, Flurin Egger wrote:
> Ben Jackson wrote:
>> I never saw an answer to this post. Anyone have an idea what I can  
>> do to verify that an email _really_ works?
> I guess it''s practically impossible. The SMTP server can have a
lot
> of reasons to reject en e-mail adress. I''m currently working on a
> "newsletter-mailing-application", we parse all e-mail addresses  
> with TMail (to make sure all adresses are according to RFC) but  
> there is no practical way (unless you want to do DNS queries etc)  
> to check if an e-mail address realy works.
DNS checks will only get you a little further than parsing  
addresses.  There is no way to check whether an email was received.   
Your best bet is to set a bounce address which ''votes against''
an
address.  Mark the address invalid when it has, say, 2-3 bounces.

Best,
jeremy

on 6/28/2005 8:21 AM Ben Jackson said the following:
> I never saw an answer to this post. Anyone have an idea what I can do 
> to verify that an email _really_ works?
If you are testing e-mail functionality, you can send an e-mail to 
yourself. If you are testing a particular user''s address, nothing is 
100% certain, see below.
>> The last step of my email validation looks like this:
>>
>> begin
>>     Mailer::deliver_complete(@user)
>> rescue Net::SMTPFatalError
>>     @user.errors.add "email", "There was a problem with
the
>> verification of your email. Please check and try again."
>> end
>>
>> It works great if the user puts in an invalid user with a valid 
>> domain, throwing the error as expected. However with an invalid 
>> domain, somehow it passes. How do I check to make sure that the email 
>> actually went through? 
>
This isn''t a rails question, it is an SMTP question.

"It works great if the user puts in an invalid user with a valid 
domain," is only true for a restricted subset of "works,"
"user,"
"domain," and the implicit, "in my environment." Some hosts
will
silently accept mail even if there is no user of that name. Those host 
may throw the mail away, or collect it to a common account, or take some 
other action, that may or may not result in the intended user seeing it. 
Your mail may be sent through a relay before arriving at the destination 
host. The relaying host will not know if the user exists. The relaying 
host may not know if destination host exists. The destination host may 
not be accepting mail. This mail may be held on the relay. It may bounce 
back to you. The bounce may come minutes, hours or days after you 
initially sent the mail.

In general there is no way to ensure that the mail went through, short 
of having the user perform some action (clicking on a link, replying) 
that confirms that they have received the e-mail.. Even if the user 
responds, there is no guarantee that they received the e-mail at the 
address that you have on file.

You say that this is the last step of a validation. What are you trying 
to validate?

Ray
-- 
newsray-BRX9mXwdik5Wk0Htik3J/w@public.gmane.org
http://www.warmroom.com

> "It works great if the user puts in an invalid user with a valid 
> domain," is only true for a restricted subset of "works,"
"user,"
> "domain," and the implicit, "in my environment."
Good point ;)
> You say that this is the last step of a validation. What are you 
> trying to validate?
All I mean is that once we''ve determined that the email fits the 
standard regexp and is not blank, we wanted to know if the email 
actually went through. Apparently this is not possible, however.

I guess we''ll have to settle with the possibility that our users might 
write "homail" instead of "hotmail", and there''s
nothing we can do
about it. Thanks for the thorough response,

Ben

Any idea if there are ruby libraries I can use to do DNS lookups?

Thanks,
ben

On Jun 28, 2005, at 7:07 PM, Jeremy Kemper wrote:
> On Jun 28, 2005, at 2:25 PM, Flurin Egger wrote:
>> Ben Jackson wrote:
>>> I never saw an answer to this post. Anyone have an idea what I can 
>>> do to verify that an email _really_ works?
>> I guess it''s practically impossible. The SMTP server can have
a lot
>> of reasons to reject en e-mail adress. I''m currently working
on a
>> "newsletter-mailing-application", we parse all e-mail
addresses with
>> TMail (to make sure all adresses are according to RFC) but there is 
>> no practical way (unless you want to do DNS queries etc) to check if 
>> an e-mail address realy works.
>
> DNS checks will only get you a little further than parsing addresses.  
> There is no way to check whether an email was received.  Your best bet 
> is to set a bounce address which ''votes against'' an
address.  Mark the
> address invalid when it has, say, 2-3 bounces.
>
> Best,
> jeremy
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

> I guess we''ll have to settle with the possibility that our users
might
> write "homail" instead of "hotmail", and
there''s nothing we can do
> about it. Thanks for the thorough response,
You could use something like this:

http://www.serviceobjects.com/products/dots_email.asp

Although it costs money, so it may not be an option.

Best,
David

Op 29-jun-2005, om 0:07 heeft Jeremy Kemper het volgende geschreven:
>> I guess it''s practically impossible. The SMTP server can have
a
>> lot of reasons to reject en e-mail adress. I''m currently
working
>> on a "newsletter-mailing-application", we parse all e-mail  
>> addresses with TMail (to make sure all adresses are according to  
>> RFC) but there is no practical way (unless you want to do DNS  
>> queries etc) to check if an e-mail address realy works.
>
> DNS checks will only get you a little further than parsing  
> addresses.  There is no way to check whether an email was  
> received.  Your best bet is to set a bounce address which ''votes  
> against'' an address.  Mark the address invalid when it has, say,  
> 2-3 bounces.
Which brings you into the territory of mailing list managers. They do  
it all (for the OP). Just some sidestepping here ;).

-- 
Regards, Charles.