Emails for Privacy and OPSEC
There are several reasons why you would want to have a virtually unlimited amount of alias email addresses. First of all, for privacy, giving out your personal email address will likely ensure a ton of spam emails. It's a good idea to have a personal email address that you only use for close family. You can also have one email address that is for trash emails, I use my old Gmail address, which I rarely check. So, what about all the other times you need to provide an email address?
There are a few solutions for this. First, you can use a service like SimpleLogin to mask your email address. This serves two purposes, one to allow you to conceal your real email address and also, to let you know who is selling your info. For example, if I use the email address walmart.1ouyq@simplelogin.com when setting up a Walmart account, and then I start receiving emails to that address that are not coming from Walmart, I can assume that they have sold my email address. Then, I can simply delete that email address from my SimpleLogin account and never receive any further emails.
SimpleLogin has a free account that allows up to 10 aliases. The premium plan is just $30 per year and allows unlimited aliases, unlimited custom domains, and a catch-all (or wildcard) domain. This is a great service, I have been using it for several years. If you happen to have a paid Proton mail account, it comes with SimpleLogin.
There is also another solution that looks more like a legitimate email address and is less likely to throw up red flags. I learned this from Michael Bazzell's podcast, which is no longer active, unfortunately. There is a website called expireddomains.net where you can purchase expired domains, some going as far back as the 90's. The reason this is a good idea is because these domains have credibility online, unlike newly purchased domains. That means that if you are using this domain to generate aliase accounts online you will have greater success. Also, if you set your new domain up with an email service, such as Proton, Tutanota, or FastMail, you can have a "wildcard". This means that no matter what email address someone uses it will come to you, as long as the @domain.com is there.
I purchased a domain for $9 that was well established and I have been using it for almost 2 years now. It's kinda fun to search through all the expired domains for one that sounds cool.