STARTTLS extension not supported by server

[Michele Simionato]

I have a CentOS machine with Python 2.4 and I wanted to install Python
2.7 on it. The installation went fine but now I have a problem with
a script sending email via TLS authentication. If I do something like

import smtplib
smtpO = smtplib.SMTP(<server>)
smtpO.ehlo()
smtpO.starttls()

I get the following error:

Traceback (most recent call last):
  File "y.py", line 5, in <module>
    smtpO.starttls()
  File "/home/rcare/lib/python2.7/smtplib.py", line 614, in starttls
    raise SMTPException("STARTTLS extension not supported by server.")
smtplib.SMTPException: STARTTLS extension not supported by server.

Notice that this not a problem of the SMTP server, since with Python
2.4 the script is connecting to the SMTP server
just fine. At first I thought the problem was with the ssl support, I
recompiled the module, but I still get
the same error. Do you have any suggestion to be debug the issue and
to figure out where the problem is?
TIA,

     Michele Simionato