You have setup a parked domain, domain2.com that points to domain1.com. But when accessing email, you are not getting email with domain2.com.
cPanel and Siteworx views this secondary domain seperate from the primary domain, so you need to setup new email account with user@domain2.com in Add/Remove accounts.
Or if you wish user@domain2.com be routed to user@domain1.com then change the mx record from domain2.com --> domain2.com to domain2.com --> domain1.com
