[Mailman-Users] DMARC hack

Allan Hansen hansen at rc.org
Sun May 24 18:02:02 CEST 2015


Much appreciated. 
Checking for aol.com and yahoo.com here alone will not work. I have a bunch of other subscribers that have
accounts with providers that are owned by Yahoo (mostly) and AOL, but whose addresses are not of this form.
I would have to do this for all addresses, to be safe.

If I do this and add the bit about the Reply-To, what would the code look like?



> On May 24, 2015, at 6:10 , Stephen J. Turnbull <stephen at xemacs.org> wrote:
> Allan Hansen writes:
>> 69,74d68
>> <     
>> <     # Added to deal with DMARC issuej
>> <     name, addrs = parseaddr(msg.get('from'))
>> <     addrs += '.invalid'
> This is known to be a bad idea, as it increases the spam score at many
> sites (because the author's mail domain doesn't resolve).  Subscribers
> at such sites may have trouble receiving mail, and your list(s) may be
> tagged as suspicious.
> I would recommend the From-munging approach:
>    name, addr = parseadder(msg.get('from'))
>    if addr.endswith('aol.com') or addr.endswith('yahoo.com'):
>        # I forget what happens if it's a bare address
>        name = "%s (%s) via list" % (name if name else "Anonymous", addr)
>        addr = <list-post address>
>        del msg['from']
>        msg['from'] = formataddr((name, addr))
> Mark (or you) probably have better code, and in some cases you may
> want to add the addr to the Reply-To field.
>> <     del msg['from']
>> <     msg['from'] = formataddr((name, addrs))
>> \ No newline at end of file

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