Looks pretty neat! Tried it out and took a quick look at the code. If I ever need a temp alias I will definitely use this. But, one thing I didn't find any info about anywhere.

Do you keep track of the deleted alias "keys". That is, if I create a mail and the key is m4m2 or whatever, I want to make sure that m4m2 will never ever lead to someone else (as well as not to me). If i register an account somewhere I obviously never want the mail going to the alias to end up at someone else either.