We have a Domino mail server protected by Iron Port (v7.1.5 I think). Iron Port reports an average 96%-97% of emails are stopped by reputation filtering, and around 3% of emails are clean messages.

Is this level of spam going to impact on our bandwidth? 

Are there other measures to prevent spam hitting Iron Port in the first place? Thanks.

**Update1**: we receive 28,000 emails a day. 27,000 of these are stopped by content filtering. 900 are clean emails.

**Update2**: The link speed is 1mbit, with 80gb bandwidth quota.

**Update3**: The sysadmin says IronPort stops the email being delivered by checking the sender. I guess this means only the header is received, which might be 1K at most, which means 27MB of rejected headers per day, which is 810MB per month, which is 1% of our quota. I think this is tolerable.

Thanks all for your help.