Originating IP Address Question POP vs. Exchange


  • Hello, got emails bounced back from a receivers domain because of a "lockout policy" from domain or IP is the question:  If the sender connects to Exchange to send POP mail then their original public IP is in the email header, is this also true if they connect via Exchange/Activesync?  I am hoping that the originating IP will be that of Exchange Public IP and not the senders current public IP (if they are at home or traveling) -- I am also finding that with our spam filter it catches emails from internal users who are on a IP that is listed with SORBS and junks them.  In the scenario I am describing with POP mail it seems that Exchange is relaying the mail (because it is noting a different IP).
    Thursday, February 25, 2016 3:04 PM


  • You can't send POP mail.  POP is a client mail retrieval protocol only.  POP clients send using SMTP.

    The IP that is of importance is the one that connects to the receiver's server.  As far as I know the IP addresses in message headers aren't generally used for antispam.  I can't see how they'd be of any use because most of them are unroutable private IPs anyway.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
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    Friday, February 26, 2016 2:57 AM