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<p>Hi all,</p>
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</span></p>
<p><span style="font-size: 12pt;">I am using NGINX as a mailproxy and recently discovered, that wireshark detects IMAP-LOGIN messages sent by nginx as "Malformed".</span><br>
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<p>The message contains: <span>Line: 3 LOGIN {18}\r\n (HEX: </span><span style="font-size: 12pt;">0000 33 20 4c 4f 47 49 4e 20 7b 31 38 7d 0d 0a</span><span style="font-size: 12pt;">)</span></p>
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<p>Some imap servers react to this with "BAD UNKNOWN Command" and close the connection. </p>
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<p>Here the full communication between nginx and backend:</p>
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<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#7f0000; background-color:#fbeded;">3 LOGIN {18}</span></p>
<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#00007f; background-color:#ededfb;">+ go ahead</span></p>
<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#7f0000; background-color:#fbeded;"><redacted user> {9}</span></p>
<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#00007f; background-color:#ededfb;">+ go ahead</span></p>
<p style="margin-left: 0px; margin-right: 0px;"><font color="#7f0000"><span style="background-color: rgb(251, 237, 237);"><redacted pass></span></font></p>
<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#00007f; background-color:#ededfb;">3 OK LOGIN completed</span></p>
<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#7f0000; background-color:#fbeded;">4 CAPABILITY</span></p>
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<p style="margin-left: 0px; margin-right: 0px;"><span style=" color:#00007f; background-color:#ededfb;">BAD UNKNOWN Command</span></p>
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<p>any ideas?</p>
<p>best regards</p>
<p>Fabian</p>
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