I went the extra mile and create a random, unique email address for every single service I sign up for, so I know precisely who sells my data to spammers if I ever get any. All the unique addresses redirect to a central one for ease of access.
It’s awesome for filtering and sorting emails though.
Report them under GDPR?
Also, it's useful for have i been pwned. One of my few accounts which uses a grouped address is in today's data dump, and it wasn't clear what account it was, because of the grouping.
It's especially good for apartment searches and job hunting. Companies that try to link buyer and seller are naturally spammy, so you create a new one for each contact. Then when you find one, you delete the others.
It's also makes it dead easy to filter all that information into folders, so you have a neat record of all your interactions with the various companies you're dealing with.
Most importantly: once you find a job / landlord / whatever, you really want a reliable line of communication. This way, your address with them never changes, but all the spam goes into the bit bucket.
Still, it mostly works. I've got 383 aliases, plus 93 disabled aliases.
Most email providers will let you create aliases, but aliases are an upsell for business plans. Tutanota lets you get more aliases, but they charge you, not kidding, 5 euros a month for 100 aliases. 10 GB of extra storage costs 2.5 euros.
Some of them advertise using address+alias@domain, but that's basically useless.
Fastmail is pretty decent with 600 aliases. That's a definite maybe.
The only one I've found with unlimited aliases is TheXYZ, and they've been around a while.