I use subdomain addresses at Fastmail aliases (both at my personal domain and Fastmail domains) for most signups. This means that I only need to keep active a few main aliases and then can create the subdomain addresses “on the fly”. Some services don’t allow subdomain addresses but do allow plus+addressing. Here is the Fastmail support page:
Fastmail subdomain and plus addressing help
Here is how this works:
- Subdomain addressing: If you control the email address test@example.com, you can use anything@test.example.com, such as bank@test.example.com and utility@test.example.com.
- Plus addressing: If you control the email address test@example.com, you can use test+anything@example.com, such as test+bank@example.com and test+utility@example.com.
- Only some email providers (including Fastmail) support one or both of these techniques. Again, the advantage is that you only need to keep one email main address or alias active, since you can add a new subdomain or plus address at any time. Years ago some sites didn’t accept subdomain or plus addresses, but in my experience there is no problem using at least subdomain addresses now.
Bill