You will need an email alias.
That is just a pointer set at email server, say alias arun_2@company.com is an alternative mailbox name for arun@company.com. Please note an alias is not a separate or new email address.
"Email aliases can be created on a Mail server. Each email alias simply forwards email messages on to each specified email address. Email aliases are often used to create handy replacements for long or difficult-to-remember email addresses"
Source:
http://en.wikipedia.org/wiki/Email_alias