The e-mail delivery may be instantaneous, or it may take as much as 15 minutes or more, depending on various factors.
Please don't make any additional requests at least within first 15 minutes of the original one. The e-mail is probably being delayed by one of the relays.

If those 15 minutes expire and you still haven't received anything - make sure you check your junk or spam mail folder.
Some email hosts, like Yahoo for example have a very bad reputation for considering valid email to be spam.