Proton Pass has a similar feature, I love it. But Spotify had banned my account and asked me to email them from the alias to unlock it, which is not possible. So you should be careful with that. A lot of companies employ anti-privacy practices.
If you’re talking about a SimpleLogin, you CAN email from it. I forget the exact terminology (I can check if you need) but you can generate a forward address that you email and the receiver (Spotify) will see it as If you have emailed from your forwarding address.
Can’t you make a reverse alias through the SimpleLogin ui? Since that’s what proton pass uses for the aliases.
You can login to the SimpleLogin.io interface and setup reverse aliases even if you create them in proton pass. They don't have the integration fully down yet so it's clunky but it works.
Firefox Relay is not free, hence why it has premium feature. Anonymous email replies and blocking promotional emails? tough shit, pay to block.
It has both a free and a Premium plan. The free plan gives you five email masks; Premium (€1 a month) gives you unlimited masks, and indeed email replies and the ability to block promotional emails.
No thanks, new kid in town https://skiff.com already provides that feature
