Anonymous email forwarding
I've not used it myself but this sounds EXACTLY what you are looking for: https://anonaddy.com/
NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.
Hackers can hack your online accounts before you even register them
1 project | reddit.com/r/programming | 25 May 2022
Images from received e-mails are cut from the body and added as attachments
1 project | reddit.com/r/AnonAddy | 18 May 2022
Which email provider do you think has the best alias management system?
1 project | reddit.com/r/PrivacyGuides | 16 May 2022
Why use SimpleLogin instead of creating aliases directly through a domain registrar?
1 project | reddit.com/r/Simplelogin | 10 May 2022
Would this app help take care of the email issue for gmail?
1 project | reddit.com/r/gsuitelegacymigration | 6 May 2022