There seem to be four cases where we need to re-write the From address (and possibly Reply-To/CC) in a message:
1) When DMARC says we have to, we re-write the From line in messages *from* that domain.
2) When someone is on a @gmail.com
domain, we need to re-write the From line in messages that they originate that we send back to them.
3) When someone is using Gmail on a different domain, we need to re-write the From line in messages that they originate that we send back to them (same as #2 except we can't use a simple @gmail.com
4) The From line in all messages sent *to* (many/most) Exchange servers.
We currently do 1 and 2. From the other topic, here are the proposed new settings:
- Per user setting to have all From lines re-written in messages to themselves.
- Per group setting to have all From lines re-written in messages sent within the group.
Shal proposed the group setting be in the default sub settings page. But I don't know how that would work. None of those existing settings have a corresponding user setting, which makes it easy to just use them when creating a subscription. If this was a default sub setting, how would we know when to use the default sub setting vs the user's setting?
I also propose a third, system wide, maintained by me list of domains that are known to run Exchange/corresponding to #4 above. This list of domains would over-rule the per-user and per-group setting in forcing From line re-writing of messages sent to those domains. I'd ask people with knowledge of these domains to send them to me.