The practice of having multiple e-mail addresses
all resolve to a single e-mail address. For example: a small business has an employee with the e-mail address email@example.com. This person is responsible for the sales and customer service of the company which have the separate e-mail addresses firstname.lastname@example.org and email@example.com to handle the business of those divisions. Mail coming in to those two e-mail addresses will be forwarded by a mail relay
to the e-mail address firstname.lastname@example.org so that the employee does not need to check three separate e-mail accounts to read the messages that are sent to the three different addresses.