I make use of the BlackBerry 7290 (with OS 4.0) and was wondering how to get the mails I sent from my BB to Outlook.
Those sent mails are too important to delete, but because my BB mailbox is getting full, I need to find some solution.

Anyone knows how to do just this?

set up auto BCC to deal w/ any new emails
forward the emails to yourself from the BB - only way to do this

Get a Gmail (2.5 GB) account and have your BIS (25-50 MB) account poll it via POP3.

Thanks for your responses, it is appreciated.

I guess that the only way to have it done properly is by getting a new BlackBerry with OS 4.1 and thus with the ability to transfer the sent items itself.

new handheld code won't make a difference - and 4.1 code is released by most carrier's i believe for the 7290

After setting up Auto BCC in the BIS, you may want to also create a filter that blocks messages FROM your email address from being delivered to the handheld.

Otherwise messages you sent will also come right back to you.