Use smtpd.PureProxy with HTTP proxy

I want to set up SMTP relay server which also needs to use HTTP proxy. I'm using Python.

SMTP proxy:

import smtpd
import asyncore
smtpd.PureProxy(('local host name', 1234), ('smtp server name', 25))
asyncore.loop()

The issue is I need to use HTTP proxy in orde开发者_Python百科r to connect to SMTP server.

How can I specify it?

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Square peg in round hole. SMTP is a different protocol to HTTP, they are incompatible.

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I used desproxy to HTTP tunnel SMTP connection.