Author pepoluan
Recipients barry, izomiac, pepoluan, r.david.murray
Date 2021-01-05.08:03:17
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Message-id <1609833798.02.0.70578529849.issue42498@roundup.psfhosted.org>
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The "problem" is that smtplib.SMTP does the following, in essence:

1. Open connection to server
2. Send EHLO
3. Read server response

The PROXY injection causes a response from the server, but the response gets "cached" in the incoming TCP buffer. The injection script likely does not consume this buffer, resulting in Step 3 above reading this "cached" response. 

So from the point of view of smtplib.SMTP, the "503" message arrives _after_ EHLO is sent, while in actuality the "503" arrives before EHLO is sent.

I suggest rewriting the port forwarding script so that it consumes the response from the server first before transferring to smtplib.SMTP
History
Date User Action Args
2021-01-05 08:03:18pepoluansetrecipients: + pepoluan, barry, r.david.murray, izomiac
2021-01-05 08:03:18pepoluansetmessageid: <1609833798.02.0.70578529849.issue42498@roundup.psfhosted.org>
2021-01-05 08:03:18pepoluanlinkissue42498 messages
2021-01-05 08:03:17pepoluancreate