[vsl]

That would only be true for only some recipients (by far not "everybody") only if Google's SPF record forbade other SMTP servers with -all. It doesn't, it uses ~all soft-fail.

Why? Precisely because of this: there are lots of perfectly legitimate situations when a third party sends email on your behalf.

Moreover, if LinkedIn signs their outgoing emails with DKIM, that would be a positive signal for a spam filter (and e.g. Gmail would show such mail as "sent via LinkedIn" or something to that effect).

[eridius]

Sounds like you know more about this than I do. I will defer to your greater knowledge.

Although "there are lots of perfectly legitimate situations when a third party sends email on your behalf" strikes me as being rather wrong. I cannot think of a single reason why anyone else should be sending email that claims to be coming from my email address. Sending email that lists me as a reply-to, sure. But as the sender? Not a chance.

[mattmanser]

It's common in enterprise products where the user's first action is in a non-email.

Like I've uploaded version 1 of the plans, added some notes and the system needs to send out an email to everyone, I did the action, it's coming from me, not the system.

There's a reason it's part of the spec.

[eridius]

You did the action, but that does not ever justify sending the email with an envelope claiming it came from you. Because you did not send the email. It could certainly put you as a Reply-To on the email, and it might possibly justify putting your name on the From line, but actually claiming to have been sent from your email address is wrong.

[mattmanser]

Says you.

However, all the clients says "why does this email come from [e-mail], I want it to come from my email address, I'm sending it".