Secondary smtp address

We use Exchange 2003 and Windows 2003 in an AD environment. Currently we have a mix of email formats. Some have firstname.lastname@company.org and some have firstnameFirstLetterOfLastName@computer.org. My company wants to make it firstname.lastname@company.org. Is there a way to add a secondary smtp address without doing it individualy till users who do not have the correct format can notify others.