It's doubtful that any of us are in a position to know if they are or not.

Let's assume, for the sake of argument, that 100% of major email providers have stated they do not sell ads based on email content.

Next we have to either: take their word for it or have the means to verify their claims.

Taking their word for it is difficult because many major email providers have a spotty relationship with honesty. This issue of honesty is not necessarily very different from other large corporations and in truth might be a factor in what made them a large corporation in the first place.

(As First Baron Thurlow is claimed to have said: "Did you ever expect a corporation to have a conscience, when it has no soul to be damned, and no body to be kicked?")

And so we would instead need the means to verify the claims of these major email providers. I'm unsure of how to reasonably do that.

►Perhaps allow Qui Tam claims for privacy issues combined with a statutorily defined "cost" for each false claim instance?

Qui tam allows, for example, private citizens to file suit against bad-actor govt contractors in the name of the govt. The "whistleblower" then receives a share of recovered proceeds.

Here, if a statutory "cost" was defined for every false claim related to using the content of email messages (say $1 per message) then this might provide a way to help verify that the major email providers are being truthful in what they claim regarding their use of content in messages.

Email providers would know their employees are on the lookout for a big payday and might honor their public promises. And if they don't, a few large qui tam lawsuits would quickly get their attention (or drive them into bankruptcy).