Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

If an email is sent from to and if it is forwarded from to

Whose authentication (SPF/Sender-ID) will be validated at, is it authentication of or ?

share|improve this question
Envelope or header? SRS in use? – womble Aug 1 '11 at 6:57

SPF works on the envelope sender - ie MAIL FROM: during the SMTP conversation, rather than the 'From:' in the body of the email.

Often these are the same. So the domain specified in 'MAIL FROM:' is first. The SPF process on the server accepting email would look up the address of the incoming SMTP server and compare it against the SPF TXT DNS record.

But then you say it is forwarded to another address at - this does not require an SPF lookup, as it is a local delivery - no other SMTP server participates.

share|improve this answer
If instead of it is forwarded to a different domain say then how the lookup will happen ? – Supratik Aug 1 '11 at 8:52

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.