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I'm trying to send an email as follows:
smtp = smtplib.SMTP(host, port=25)
smtp.ehlo()
smtp.sendmail(from_mail, to_mail, data)
The last line / command calls the raise.
I would like to know the reason why SMTP did not accept my email?
In theory, enough to capture the exception.
However, the exception of the last line returns:
"smtplib.SMTPServerDisconnected: Connection unexpectedly closed"
This is because the smtplib get replies in:
http://hg.python.org/cpython/file/default/Lib/smtplib.py
 767 (code, resp) = self.data(msg)
Then performs:
 769 self.rset()
As a result, the SMTP server disconnects the client. And instead receive info with reason I have information about sudden disconnection.
I do not think it should be reset, and if it is wrapped in a try.
Working snippet:
(code, resp) = self.data(msg)
if code != 250:
 #self.rset()
 raise SMTPDataError(code, resp)
#if we got here then somebody got our mail
return senderrs
This happens on servers mx.google.com