Thanks for clearing that out!

Then my next question would be: is there something that would implement 
SRS in forwarding within XMailserver?

Sincerely,
Bart Mortelmans



CLEMENT Francis wrote:
>> -----Message d'origine-----
>> De : [EMAIL PROTECTED]
>> [mailto:[EMAIL PROTECTED] la part de Bart Mortelmans
>> Envoy=E9 : vendredi 27 avril 2007 09:41
>> =C0 : [email protected]
>> Objet : [xmail] Re: Dynamic DNS / Don't use SPF
>>
>>
>> SRS has a couple of problems, which make me assume that it's not going =
>>     
>
>   
>> to really get anywhere:
>>
>> 1) If you implement SPF, then you have to rely on the fact that=20
>> forwarding services of your recipients implemented SRS.
>>     
>
> The "mail from" rewrite done by srs on forwarded mails will be used as =
> is by
> any no 'srs' intermediate server on any next hops in the route to the =
> final
> server (that have not to be 'srs' too)
>
>   
>> 2) The from address gets mocked up. Making it not very "user =
>>     
> readable".
>
> NO, it's the SMTP "MAIL FROM" that is changed NEVER the 'From' field in =
> the
> mail itself
> The 'user' never see the 'Mail From' in any mua 'normal' views, but =
> only
> when wanting to view de complete headers and if the smtp servers added =
> some
> info about the real 'mail from' used in the smtp transaction.
> The 'From' is not derived from the SMTP "MAIL FROM", as the From is =
> allready
> in the mail header and written by the sender mua=20
>
>   
>> 3) The from address SRS created would change from time to time (it=20
>> includes a time stamp). So the same person sending me two=20
>> mails, has two=20
>> different addresses.
>>     
>
> Yes at smtp level, false at 'mua' level :)
> The final user see exactly the same address
>
>   
>> 4) The from address SRS created is meant to expire (otherwise=20
>> abuse via=20
>> such an address would be possible). So replying to that e-mail you=20
>> received last week, won't work. Sure, you know all about SRS,=20
>> so you're=20
>> able to find out what the real address of the sender was. But=20
>> will your=20
>> mom be able to do so?
>>     
>
> False, as said, the mua use the From and Reply-to 'mail header' fields, =
> not
> the smtp "MAIL FROM" that they dont know nothing.
> So replying is ok and never change.
>
>   
>> Basically it comes down to this:
>> If you implement SPF, then you could assume that e-mails you send from =
>>     
>
>   
>> servers that are "trusted" according to SPF and that don't get=20
>> forwarded, are more likely to get through the spam filters.
>> But your SPF record is best to also allow mails from other servers=20
>> simply because you never know if your recipient might be using=20
>> forwarding.
>>
>> Sincerely,
>> Bart Mortelmans
>>
>>
>>
>>     
>
> Francis
> -
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