Problem:
Since updating to IOS 4.2.1 I’ve noticed a change in behavior in the mail delete icon. It now switches states between and Archive and Delete button depending on the email or the account.
Solution:
Open Settings
select the mail, Contact, Calendars
Select the account that is give you the problem as in archive messages
the if you look at the last option Archive Messages turn it off if you want delete or turn it on to archive them
