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-   -   Is the SMTP safe? (

Kira 29th September 2011 03:45

Is the SMTP safe?

I just found out I can connect to my SMTP Server via pythons smtplib without the need to login and send mails to whatever address with a random 'from'-address.

I did some relay tests online and they all say it's relay safe.. but... is it a correct behaviour?

As an example:


smpt = smptllib.SMTP('')
smpt.sendmail('', '', '....;)

This works, and I am doing this from remote, not locally on my Server.


till 29th September 2011 10:35

Yes, thats the correct behaviour.

There are 3 possibilitys where every mailserver ahs to accept emails:

1) The email is from localhost
2) The email is sent from a server that we allow to relay. See mynetworks setting in
3) The recipient domain is a local domain of this server.

Kira 29th September 2011 11:11


thanks for your answer.

I did the test above from my machine at work.
None of the 3 points you mentioned match this machine - I think.

So is this realy correct?


till 29th September 2011 11:13

Use this test to find out if your machine relays:

Leave the email field empty or use a external address like gmail.

If you followed the perfect setup guide to install your server, then it is no open relay.

Kira 29th September 2011 12:00

Okay, seems to be safe.. :)
Though I don't understand why I can do what I described above..

Thanks a lot,

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