mouss wrote:
there are two cases:
- you enforce authentication and sender-login match. in this case, you detect forgeries
Lots of people like to allow authenticated users to send messages out with their own choice of FROM address (you paid for an smtp service - my opinion is that you should be allowed to use it for all your messages...). Possibly I misunderstand sender-login maps on postfix though and this is actually allowed (does it work by stopping you pretending to be another local user, but NOT limiting you from being a random other user, eg xxx@abcd.com ?)
- you don't. in this case, you can't detect forgeries. and a header won't help. the whole approach breaks.
His point was that the header could be added at the client end - not all that scalable, but a good idea.
What seems to be missing from postfix (my understanding), but would be very useful, is a map which is based on authenticated sender name (we have maps based on FROM, but not authenticated user...) - this would allow stuff like more flexible restrictions on what a user can do based on the user themselves rather than the FROM address they are using... Possibly my misunderstanding though?
The extra header field was being added presumably to identify real sent mail from faked spam and hence only add real sent messages to the sent folder?
and how do you add a header only to "really" sent mail? and anyway, how do you deliver a _copy_? remember that this is outgoing mail and won't naturally go through dovecot.
Perhaps I misunderstand the idea - but what I think was wanted was that every sent email from an authenticated sender would be bcc'd back to the person it came from. Then when it's being delivered back to the person who sent it (ie deliberate mail loop back) we detect that it's our own message "bouncing" back and stick it in the sent items folder instead of the inbox. The finesse is then reliably detecting which is which....
The point raised later in the thread is that it's quite hard to detect mail being bcc'd back to us for putting in sent items and mail being dropped onto the server with a forged FROM address. As you correctly point out some restrictions on authenticated user help. The previous poster pointed out that hard to guess client headers inserted in all genuine email are also useful
I think we are all trying for the same thing, but anyway...
Good luck
Ed W