Most bad guys are lazy and use massive lists to spam that they acquire from wherever.
The advantage of using an alias address is when one of the places you put an alias into is compromised or "sharing" your email address, depending on your mail server options, you can limit where you allow messages to that address to arrive from or even just automatically delete emails to that address.
This is superior to email tags. Email tags use the format [email protected]
, and the receiving mail server will ignore then +tag
part and deliver to the inbox of [email protected]
. It is trivial for a spammer to remove the tags even on a large list, so you give up your full email address to the spammer, whereas an alias is a full email address and cannot externally be determined to be an alias.
It is exceptionally difficult to use email and be completely anonymous, especially since ICANN and registrars rapidly de-register domains that are discovered to have been created with fictitious names and addresses, so this is not an anonymization tool unless you have a domain that many different users use, because then to be specifically identified you user data must be somehow discernible from other users of the domain.
Note that using third-party mail providers as anonymizers comes with the risk that you are discovered to be violating their Terms of Service and they immediately close the account without any recourse.
You may discover that 100 aliases is not that many compared to how many different accounts you are setting up with a unique alias. This can be simplified by combining aliases and tags. If you use the format [email protected]
for every forum account, and later find spam being delivered to [email protected]
, then you can create the alias [email protected]
, but you have to change addresses with all forums using that alias plus tag, which is more effort than just changing one alias per account.