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I did some work with an organization and had a falling out, so I left them. They used postfix to have emailaddresses@theirdomain.com, and I had one. I set up gmail to get my mail via POP as well as to "send mail as @_.com". I think for a long time they forgot to delete my email address and now it seems that I can send but not receive mail at the address. What could a possible explanation for this be? Can they revoke delivery but not sending from the address? Why would they only revoke one if they cna revoke both? Is it more tedious or difficult a task to revoke sending?

Thanks

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closed as off topic by kce, womble, Mircea Vutcovici, sysadmin1138 Jun 30 '12 at 2:37

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That e-mail address was never yours to begin with. –  womble Jun 30 '12 at 2:25
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Fine but my question was technical not philosophical. –  Name Jun 30 '12 at 16:00
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3 Answers

up vote 2 down vote accepted

I can put a letter in the mail that says it's from the President. But if you send a letter to the President, I can't get it. They removed the email address, so mail sent to it now goes anywhere. However, you can still send a mail with any from address you choose to put in it. (Other sites may reject the sender as invalid or they might not.)

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If a site were to reject the sender as invalid, what would it do such a thing based on? –  Name Jul 12 '12 at 5:20
    
I mean, what criteria would it use to judge a sender's validity? BTW, great explanation! –  Name Jul 12 '12 at 5:21
    
@Name: SPF or DKIM. –  David Schwartz Jul 12 '12 at 5:23
    
Thanks again... –  Name Jul 12 '12 at 6:16
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Gmail has two methods of sending emails:

  1. Using the organizations SMTP server
  2. via Google, just setting a From: header

You have selected the second one. Your emails are bypassing the organizations SMTP server entirely, which is why sending still works.

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Thanks for actually answering the question. :) –  Name Jun 30 '12 at 16:01
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I believe your account got deleted, but because you registered it before in gmail.com they basically still thing that you are allowed to send email from that address.

The thing is that SMTP protocol (RFC 821, RFC 2821, etc) can't really check that if you really own the address used in MAIL FROM header. So as long you match other criteria like valid ip, correct header, etc the SMTP server will forward your email.

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Valid IP? What criteria does it check the IP against? Thank you for he answer. –  Name Jun 30 '12 at 16:02
    
That was just an example based on what some smtps server accept your email for delivery. In your case google.com let you send emails from the old .com email, because you are using their SMTP server and you registered the address before. –  golja Jul 1 '12 at 4:26
    
I see, but that's assuming that I'm still using google's SMTP servers just with my pre-verified "from" address. Is it possible for them to revoke my ability to send mail through their SMTP server, since you said that SMTP itself doesn't do any authentication? Also, is there any way at all for me to tell which method is being used? If there isn't any indication provided by GMail's GUI, then is it possible for me to tell based on the raw headers of a given message that I send from that address to a recipient account that I control? –  Name Jul 1 '12 at 8:17
    
Since headers can be spoofed, not definitively, no. Maybe Google adds an X-Original-To: header, you can check for that. –  adaptr Jul 4 '12 at 14:13
    
thanks :) [dummy chars to reach min cmt length] –  Name Jul 11 '12 at 17:12
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