I've used VERPs¹ sometimes, even for individual mail. It's a pity that so few general-purpose email clients will generate them out of the box. You can make it h

I've used VERPs¹ sometimes, even for individual mail. It's a pity that so few general-purpose email clients will generate them out of the box. You can make it happen with MTA configuration, which is one of many reasons I still run my own mail server. [1] https://en.wikipedia.org/wiki/Variable_envelope_return_path https://en.wikipedia.org/wiki/Variable_envelope_return_path