customers not being recognised by sugar plugin for outlook

Some of our customers are not being recognised by the Outlook plugin

even on creating a customer through the plugin it then does not link the emails to the contact card. I have a suspicion it is due to the formate of the email address

first name last name <firstname.lastname@customeraccount.com.au> where the sugar customer record only has firstname.lastname@customeraccount.com.au

this is very frustrating as this is a key feature that we use for maintaining correct records of customer contact.