Question

I am trying to make a simple Python filter for postfix, to add in a ‘Reply-to’ header to certain messages.

What I’ve done so far is to take the email from stdin, and parse it into an email object like so:

raw = sys.stdin.readlines()
msg = email.message_from_string(''.join(raw))

Then I’ve played with headers etc.

msg.add_header('Reply-to', '[e-mail]')

And now want to re-inject that back into postfix. Reading the filter readme associated with postfix, I should pass it back using the ‘sendmail’ command. However, I’m not sure how to pass the email object over to sendmail, for example using subprocess’s ‘call()’ or whether I should use the smtplib’s ‘smtplib.SMTP()’?

What would be the ‘correct’ method?

Thanks

Answer 1

You should be able to use both methods, but smtplib.SMTP() is more flexible and makes the error handling easier.

If you need an example, have a look at my framework for python filters:
https://github.com/gryphius/fuglu/blob/master/fuglu/src/fuglu/connectors/smtpconnector.py#L67

the re_inject method does exactly that (FUSMTPClient is a subclass of smtplib.SMTP), so basically it boils down to:

client = smtplib.SMTP('127.0.0.1',<yourportnumber for the receiving postfix instance>)
client.sendmail(<envelope from>, <envelope to>, <yourmessageobject>.as_string())