As the title suggests, what is the name or the best way of referring to the second mail accounts many users on the internet open only for unimportant websites in order to avoid being spammed.
Disposable mail addresses are another thing, and spam mail accounts is too generic and would conflict with thousand of results searches for "how to avoid spam on my mail account".
EDIT: They also are not throwaway addresses or temporary emails because people use them for extended periods of time and even forever as "unofficial email" just for unimportant websites.