The concept involves utilizing Gmail’s feature to ignore periods within usernames, coupled with the addition of plus signs followed by unique identifiers. Gmail recognizes all variations of a username with or without periods as the same address. For example, if the primary address is johndoe@gmail.com, Gmail also delivers mail sent to john.doe@gmail.com, or j.o.h.n.d.o.e@gmail.com to the same inbox. Furthermore, the “+” symbol allows for variations like johndoe+newsletter@gmail.com or johndoe+shopping@gmail.com, all directed to johndoe@gmail.com.
This technique offers a practical way to filter incoming mail, categorize subscriptions, and track the source of email lists. It proves particularly beneficial for managing multiple online registrations and identifying which services might be sharing contact information. By providing a unique “+”-modified address to each service, one can easily determine the source of any spam received.