In FIMS you can use the "Alternate Address" tab to store as many email addresses as necessary. 

I really would request that there are two email address fields - one for the primary email address and one that can hold a list of addresses. That way you can control whether you want a particular mailing to go only to a primary address or all addresses you have for a profile. It also creates problems with things like CRM sync to have multiple email addresses in the same field so keeping a field that is only one address would be needed. But having a field that can hold the list would be really useful instead of needing to create an alternate address record for every additional email address.