What to do when one mail recipient fails out of several?
There is currently a poposal to make MailHost transactional, so you can be sure that you sent the mail. However, when you have multiple recipients, that doesn't solve the problem, because then you actually get "half done" transactions. Smtplib.SMTP.sendmail is nice enough to send back a list of which mails failed, but Zope can't really do much with that list. If it returns an error, the user will resend the mail to all recipients, if it ignores it (as today) the user will think all mails went through. The problem really lies in the binary mode of error/success that web will have in this case. There is no partial success, either you get up an error page or you don't. My thought about how to solve this is to make an addition to smtplib.SMTP.sendmail(), an new parameter "stopOnRcptErr" or something, that defaults to "False", which gives todays functionality. MailHost could then call smtplib.SMTP.sendmail with stopOnRcptErr=True, which would then raise a SMTPSenderRefused error if any of the recipients fail. My questions: 1. What do you think? Is this reasonable? 2. Does anybody know where to send suggestions for changed Python stuff? python-help doesn't seem right...
This approach makes no sense. Email uses the store-and-forward principle. This means your local mailserver could accept the delivery but it can never guarantee you that the mail is really delivered to the recipients. It can only confirm that it accepts the email for delivery and nothing else. Andreas ----- Original Message ----- From: "Lennart Regebro" <lennart@regebro.nu> To: <zope-dev@zope.org> Sent: Thursday, November 15, 2001 06:34 Subject: [Zope-dev] What to do when one mail recipient fails out of several?
There is currently a poposal to make MailHost transactional, so you can be sure that you sent the mail. However, when you have multiple recipients, that doesn't solve the problem, because then you actually get "half done" transactions. Smtplib.SMTP.sendmail is nice enough to send back a list of which mails failed, but Zope can't really do much with that list. If it returns an error, the user will resend the mail to all recipients, if it ignores it (as today) the user will think all mails went through.
The problem really lies in the binary mode of error/success that web will have in this case. There is no partial success, either you get up an error page or you don't.
My thought about how to solve this is to make an addition to smtplib.SMTP.sendmail(), an new parameter "stopOnRcptErr" or something, that defaults to "False", which gives todays functionality. MailHost could then call smtplib.SMTP.sendmail with stopOnRcptErr=True, which would then raise a SMTPSenderRefused error if any of the recipients fail.
My questions: 1. What do you think? Is this reasonable? 2. Does anybody know where to send suggestions for changed Python stuff? python-help doesn't seem right...
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Hmm, thats true... But in this case it doesn't accept it for delivery, and the sender doesn't get to know that either. I realized that in most cases it's not a problem, since mostly MailHost is used to send mailforms to a specific set of recipients, and then you don't want to tell the website visitor that one address didn't work, as long as another one did. So maybe it's not much of a problem. I still don't like it though, which is why I'd like the option of selecting the behaviour. :-) ----- Original Message ----- From: "Andreas Jung" <andreas@andreas-jung.com> To: "Lennart Regebro" <lennart@regebro.nu>; <zope-dev@zope.org> Sent: Thursday, November 15, 2001 1:08 PM Subject: Re: [Zope-dev] What to do when one mail recipient fails out of several?
This approach makes no sense. Email uses the store-and-forward principle. This means your local mailserver could accept the delivery but it can never guarantee you that the mail is really delivered to the recipients. It can only confirm that it accepts the email for delivery and nothing else.
Andreas
----- Original Message ----- From: "Lennart Regebro" <lennart@regebro.nu>
My thought about how to solve this is to make an addition to smtplib.SMTP.sendmail(), an new parameter "stopOnRcptErr" or something, that defaults to "False", which gives todays functionality. MailHost could then call smtplib.SMTP.sendmail with stopOnRcptErr=True, which would then raise a SMTPSenderRefused error if any of the recipients fail.
I like the idea of having this capability. Having the option to integrate it into sendmail or as a standalone scrubber would be ideal. Could this become a product? Next week I get a new list of 500 emails that has never been tested. I would like to do an SMTP handshake(without sending) to verify the domains/addresses that will accept the emails, and remove the addresses that fail. This makes bounce management much cleaner and lowers overhead when you actually send the messages. -Trevor
-----Original Message----- From: zope-dev-admin@zope.org [mailto:zope-dev-admin@zope.org]On Behalf Of Lennart Regebro Sent: Thursday, November 15, 2001 7:38 AM To: Andreas Jung; zope-dev@zope.org Subject: Re: [Zope-dev] What to do when one mail recipient fails out of several?
Hmm, thats true... But in this case it doesn't accept it for delivery, and the sender doesn't get to know that either. I realized that in most cases it's not a problem, since mostly MailHost is used to send mailforms to a specific set of recipients, and then you don't want to tell the website visitor that one address didn't work, as long as another one did.
So maybe it's not much of a problem. I still don't like it though, which is why I'd like the option of selecting the behaviour. :-)
----- Original Message ----- From: "Andreas Jung" <andreas@andreas-jung.com> To: "Lennart Regebro" <lennart@regebro.nu>; <zope-dev@zope.org> Sent: Thursday, November 15, 2001 1:08 PM Subject: Re: [Zope-dev] What to do when one mail recipient fails out of several?
This approach makes no sense. Email uses the store-and-forward principle. This means your local mailserver could accept the delivery but it can never guarantee you that the mail is really delivered to the recipients. It can only confirm that it accepts the email for delivery and nothing else.
Andreas
----- Original Message ----- From: "Lennart Regebro" <lennart@regebro.nu>
My thought about how to solve this is to make an addition to smtplib.SMTP.sendmail(), an new parameter "stopOnRcptErr" or something, that defaults to "False", which gives todays functionality. MailHost could then call smtplib.SMTP.sendmail with stopOnRcptErr=True, which would then raise a SMTPSenderRefused error if any of the recipients fail.
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From: "Trevor Toenjes" <zope@toenjes.com>
I like the idea of having this capability. Having the option to integrate it into sendmail or as a standalone scrubber would be ideal. Could this become a product?
Uhm, no, I don't think so. This is more a question of weather to add an option to make MailHost/sendmail fail if one reciepent is rejected or only when all recipients are rejected as it is today. I'm still not sure it's a very useful idea though. :-)
Next week I get a new list of 500 emails that has never been tested. I would like to do an SMTP handshake(without sending) to verify the domains/addresses that will accept the emails, and remove the addresses that fail. This makes bounce management much cleaner and lowers overhead when you actually send the messages.
If you call sendmail directly without going through MailHost you will get a list back of the rejected recipients. Maybe you could use that?
On Thu, 15 Nov 2001, Trevor Toenjes wrote:
Next week I get a new list of 500 emails that has never been tested. I would like to do an SMTP handshake(without sending) to verify the domains/addresses that will accept the emails, and remove the addresses that fail. This makes bounce management much cleaner and lowers overhead when you actually send the messages.
This is not actually possible with SMTP. Various MTAs do have the functionality to let you know if they can route to that domain, but that still does not guarentee that the username will be accepted, or that the MX host for that domain is actually accepting mail. -Matt -- Matt Hamilton matth@netsight.co.uk Netsight Internet Solutions, Ltd. Business Vision on the Internet http://www.netsight.co.uk +44 (0)117 9090901 Web Hosting | Web Design | Domain Names | Co-location | DB Integration
----- Original Message ----- From: "Matt Hamilton" <matth@netsight.co.uk> To: <zope-dev@zope.org> Sent: Thursday, November 15, 2001 09:33 Subject: RE: [Zope-dev] What to do when one mail recipient fails out of several?
This is not actually possible with SMTP. Various MTAs do have the functionality to let you know if they can route to that domain, but that still does not guarentee that the username will be accepted, or that the MX host for that domain is actually accepting mail.
That's the point. The feature is highly dependant of the underlying mail system and it makes less sense to support this issue in the Zope core. You can always subclass Mailhost and write a customized version and publish it but I believe it is not very suitable for the Zope core distribution. Andreas
Matt Hamilton wrote:
On Thu, 15 Nov 2001, Trevor Toenjes wrote:
Next week I get a new list of 500 emails that has never been tested. I would like to do an SMTP handshake(without sending) to verify the domains/addresses that will accept the emails, and remove the addresses that fail. This makes bounce management much cleaner and lowers overhead when you actually send the messages.
This is not actually possible with SMTP. Various MTAs do have the functionality to let you know if they can route to that domain, but that still does not guarentee that the username will be accepted, or that the MX host for that domain is actually accepting mail.
-Matt
Apparently _some_ of this is possible. A couple of weeks ago, I was facing a similar situation, and found a site on the web that would do validation of email addresses by (IIRC) sending a mailto header to the mail domain and looking at the response. It did not work for all domains, notably hotmail and yahoo would not tell whether the address was OK or not. But a few smaller isps would work. Unfortunately, I cannot find that site now. But this morning, I found something that might be better if you can translate asp -> python. http://coveryourasp.com/ValidateEmail.asp YMMV. -- Jim Washington
From: "Jim Washington" <jwashin@vt.edu>
Apparently _some_ of this is possible. A couple of weeks ago, I was facing a similar situation, and found a site on the web that would do validation of email addresses by (IIRC) sending a mailto header to the mail domain and looking at the response. It did not work for all domains, notably hotmail and yahoo would not tell whether the address was OK or not. But a few smaller isps would work. Unfortunately, I cannot find that site now.
Yes, you can look up the domain, find the mailhandler, open a connection, do a MAIL FROM and a RCPT TO to the address in question. If that goes OK, the mail shouldn't bounce. There is a dns module at http://www.interlink.com.au/anthony/ , and then it should not be too hard to make something that verifies e-mail addresses. That might be rather handy... But I won't need one for a couple of months so I'm not doing it. :-)
Folks, I might be wrong, but I think we are kinda missing the point in this discussion. As was mentioned before, the SMTP system operates in a store and forward mode, and you can never be sure of the arrival of the message just because the SMTP server in front of you accepted it for delivery However, once the SMTP server has accepted it for delivery, the SMTP system will make every efort to notify the sender in case of failure, whereas if the SMTP server rejects some recipients, it is Zope's responsibility to notify the user. So I think that we should be configuring the SMTP server Zope talks to to accept all e-mail for delivery and check later, so that the sender be notified of failures, otherwise we end up dealing with a maze of possibilities for defining success or failure in Zope. Just my 2 cents Cheers, Leo
Apparently _some_ of this is possible. A couple of weeks ago, I was facing a similar situation, and found a site on the web that would do validation of email addresses by (IIRC) sending a mailto header to the mail domain and looking at the response. It did not work for all domains, notably hotmail and yahoo would not tell whether the address was OK or not. But a few smaller isps would work. Unfortunately, I cannot find that site now.
But this morning, I found something that might be better if you can translate asp -> python. http://coveryourasp.com/ValidateEmail.asp
Jim, Yes, this is real close to what I need to do in Zope. Thanks. I use Formulator for the email syntax validation from a form. But emails are universal, it would be nice to have built-in validation. My python is very weak but, It would be interesting to see something like this in Zope...from http://www.hexillion.com/software/components/HexValidEmail/ To see how easy it is to check syntax, domain, and username, take a look at these two lines of VBScript code: Set oVE = Server.CreateObject("HexValidEmail.Connection") If 0 = oVE.Validate("test@example.com",3) Then 'it's bad -Trevor
participants (7)
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Andreas Jung -
Andreas Jung -
Jim Washington -
Lennart Regebro -
Leonardo Rochael Almeida -
Matt Hamilton -
Trevor Toenjes