Hi,
On Fri, 15 Aug 2003 15:59:42 +0300, you wrote:
> Does anyone know if these days Yahoo sends out their e-mails via
> an intermediate server called sun.mmic.net ??
>
> I do some checks for Yahoo servers to keep spammers at bay. If the
> mail is not delivered DIRECTLy by Yahoo servers to my server then I
> politely reject it. A new development has caught me unawares though:
>
> I have some funny scenario here:
>
> A user johdoe@??? sends an e-mail to mabibi@???. This
> mail is forwarded to validclient@???
>
> When this mail hits wananchi.com, it's arriving via sun.mmic.net. Now
> I am wondering if this is a valid Yahoo server??? Shall I trust it?
>
> Below is one e-mail that johdoe@yahoo receives once I have rejected
> their mail (because it's not from a Yahoo server). :-))
I think the answer is in your question. johdoe@yahoo sends mail to
mabibi@??? and this address is forwarded to
validclient@???.
This means, that the message with the yahoo sender address is
delivered from the mailserver handling mabibitours.com to your server.
That's why Adam asked if that server is an MX for this domain.
BTW: It doesn't have to be, as the inbound (MX) and outbound servers
for a domain don't have to be the same and you don't need an MX record
for an outbound-only server.
Anyway, if you want to allow your users to receive mail from yahoo,
even if it got redirected from another address, you can't check the
delivering server, it simply is not a yahoo server in that case.
I didn't find any possibility to check for a legitimit yahoo message,
as the server check doesn't work and yahoo doesn't insert any hint it
originated from their servers (hotmail inserts a header line, not 100%
sure as that one can be faked, but most spam doen't have that line).
Cheers,
Oliver
