You can go to gmail and there is an outline that will tell you how to set up your email on your phone. if you go into the email set up on the 7230, its self-explaintory. You cant have it set up to delete from your gmail, (i dont think) but when you go to the bwc, www.tmobile.com/bwc
you can set it up to delete the email in there when it's deleted from the handset.
I recommend just forwarding your gmail to your berry so that sent mails dont go directly to the berry too. If you dont forward it and just put it in your berry, it will take roughly 15 minutes for the email to get to the berry. Forwarding it will take between 1-15 seconds.