Thank you very much for the answer. If I modified the headers the user it will not understand why it cannot reply direct to the email. I find strange that sieve do not have an option to encapsulate the email.
I will try to modify the headers in order to do some test. Thank you very much to your fast and clear response. On Thu, Sep 17, 2015 at 2:18 PM, Sebastian Nielsen <sebast...@sebbe.eu> wrote: > The best thing here is to set up a header filter that replaces first From: > header with your adress, and first To: header with the destination gmail > adress. > To prevent that any spam blacklisted adresses appear, discard every to: > and cc: header after this. > Then you ensure the MAIL FROM in the SMTP communication with gmail, states > your adress and not Yahoo’s. Add a SPF record to your domain, and then you > are done. > > If you want to go the encapsulation way, it gets a little bit more > complicated, and you need some sort of milter or post-processing filter to > encapsulate the email. > > *From:* Il Neofita <asteriskm...@gmail.com> > *Sent:* Thursday, September 17, 2015 8:12 PM > *To:* Sebastian Nielsen <sebast...@sebbe.eu> > *Cc:* postfix-users@postfix.org > *Subject:* Re: Forward rejected by yahoo > > Thank you very much for the fast reply. > I was looking on sieve or postfix and I do not find how I can do it. > Since I believe that will be the best way to do it. > Can you help me out? > > Thank you > > > On Thu, Sep 17, 2015 at 1:51 PM, Sebastian Nielsen <sebast...@sebbe.eu> > wrote: > >> No. >> SPF is designed to be secure, eg you cannot add some header to bypass the >> authentication, then every phisher would add such a header. >> >> What you need to do, is to rewrite the FROM adress or encapsulate the >> email. >> Rewriting FROM adress can be as simple as rewriting yourn...@yahoo.com >> to yourn...@yourserver.tld , or even yourname.yahoo....@yourserver.tld >> Then you host a own SPF record. >> The disadvantage of this method, is that it will not be possible to reply >> or answer on emails from your google account. You could however, since you >> know the domain and username, manually write the correct @yahoo.com >> adress in the “to” field when replying to a email. >> >> Another way, is to encapsulate the email in a new message/rfc822 >> container, where the outer container contains like From: >> forwar...@yourserver.tld To: somen...@gmail.com , Subject: Fwd: Original >> Subject >> And then the inner container contains: >> From: yourn...@yahoo.com >> To: yourn...@yourserver.tld >> Subject: Original Subject >> >> The advantage with this method is that you can reply to the email by >> replying to the inner container. This is how most email clients forward >> email, by encapsulating them. >> In most cases, a email client will either show a iframe showing the >> original content, a button to open the mail in a new window, or a attached >> file that can be opened to show the mail. >> >> Of course, its important that you do publish a own SPF record. >> And also, its a bad idea to forward spoofed email, since this could get >> your domain “blacklisted” at google, thus its a good idea to SPF and/or >> DKIM check any incoming email on your forwarder adress before forwarding >> them. >> >> *From:* Il Neofita <asteriskm...@gmail.com> >> *Sent:* Thursday, September 17, 2015 7:40 PM >> *To:* postfix-users@postfix.org >> *Subject:* Forward rejected by yahoo >> >> Hi, >> I have the following problem if I forward an email received from yahoo to >> an other yahoo account the message is rejected. >> If I send a message from yahoo -> my server and forwarded to a google >> account the message is marked as spam, since is considered a spoofed. >> >> Can I fixed this adding some header? >> >> Thank you >> > >
