An email address consists of a specific format.
- username : Identifies the user.
- @ : Separate the string of characters.
- host_name : The most specific part of the host name appears first, before the period which pronounces as "dot". After that you can see more general destination names.

 

Abbreviations can use for mailbox addresses. Abbreviations allow a company to establish short names for each of its departments.  So that it is possible for employees in the company to address mail without typing long suffixes