[adityar]

if they're using hashed emails for tracking, we're pretty much clucked. There is an option in gmail that can prevent this.

if your email is [e-mail], use [e-mail] (gmail will ignore the stuff after the + ). You can also use . separators.

Now, to keep track of that...

[nitrogen]

Since Gmail's account name semantics are well known, the top data collecting agencies have no doubt adapted by now.

Also, frustratingly, a lot of sites will break, often silently, if you give them an e-mail address with a plus symbol (e.g. it might end up in a GET request to an internal API without proper escaping, and be interpreted as a space).

[Amadou]

Yes, the only way to go is your own domain. Use an add-on like Virtual Identity for Thunderbird to keep track of which From address goes with which recipient. https://www.absorb.it/virtual-id (their cert seems to have expired over the weekend)

[Evbn]

I do wonder when/if trackers collapse all addresses on a small domain into a glob. They totally could.

[chrishepner]

Whether this works depends on the site's email validation script: many don't allow the '+' character.

Gmail filters out '.' within usernames (e.g., [e-mail] and [e-mail] are sent to the same account), but this gives you a more limited number of options, and is even harder to keep track of!