I’ve come across a neat method to generate email addresses for individual services. I want to figure out some way to set up a filter such that, if an email comes in not matching an existing address, it goes through a validator to ensure the checksum at the end of the local part is correct, before forwarding it on to my inbox. I know how to implement the code side of this, but I’m not sure how I would hook this into Postfix and Dovecot. Does anyone have any ideas on how that part would be done? I’m thinking I’ll also use either SHAKE256 with a 6-byte alphanumeric output, or some other SHA function with XOR folding, for compactness. The original function on that website uses just the first few bytes of an md5 checksum.