Disposable Yahoo! email address can be made on top of their original Yahoo! email. Gmail has similar thing by letting you receive emails sent to firstname.lastname@example.org in the email@example.com account, but sooner or later spammers will spam your original address because the prefixes are the same. To make a truly disposable Gmail address with alternative base name:
- Create a new Gmail (preferably with shorter name).
- Set auto forwarding from the new Gmail to primary Gmail.
- In the primary Gmail, create a filter having "basename OR basename+ -keyword" in the "To:" field, where firstname.lastname@example.org are given out.
- In the next step, select whatever you want to do with the spams, say "delete".
Filters are not set up in the new Gmail (and hence step 2) so that no logout is needed to modify the filter. The "To:" field allows about 1400 characters, so many disposable addresses can be filtered (even if it is full, create up to 20 filters, or even get create in the new Gmail or at worst, get another new Gmail for more filters...).