Re: misconception in SPF

2012/12/7 Paul Smith <[email protected]>:

> This problem is really due to the (IMHO horrible) allowance for an A record
> to be sufficient for mail delivery. However, it would be quite hard to
> remove that allowance nowadays. I don't know the stats for how many email
> addresses use A records for delivery rather than MX, but I'd guess its a
> significant number.

I think you are confused about the MX on the receiver side and the A
record of the sender !
Mails are sent to MX for a domain but the sender has not to have a MX
record to send !

The problem here is that the sender uses a forged address which has an
A record. What you said is that the recipient should not be an A
record and should be an MX. They are two different things !

> As a random thought, would there be the possibility to add some sort of
> marker on a parent domain to say 'we understand MX records, so we don't use
> A records for mail within this domain'? So, if you receive mail from
> 'bibble.twitter.com', you check the TXT records for 'twitter.com' which tell
> you that subdomains/hosts without an MX record won't have mail, and since
> there isn't an MX record for 'bibble.twitter.com', you can reject it/treat
> it as spoofed.

same as above. MX for bibble.twitter.com is only to receive emails.
Nothing prevents [email protected] to send unless you put a
TXT "v=spf1 -all" for it !