If I were you, I would not use the carrier supplied email address at all, for several reasons. I assume this is what you mean by "blackberry email".

First, you will open yourself up to receiving more SPAM that you care to get. that account is unfiltered and I have not heard of a SPAM filter for a BB.

Second, you do not own that address. Therefore, you cannot take it with you when and if you leave your current carrier. Plus, it can change at any time. Not likely to happen, but there is always the possibility.

And last, you can only check that email on the BB itself. There is no web-based email solution nor can it be downloaded to your PC in an email client such as Outlook or Thunderbird, etc. And as an FYI, there is a scheduled RIM outage this Sunday from 2 AM to 6 AM Eastern.