An anonymous reader writes "Our organization had had a decent SPF record of our own for a long time. Recently, we decided to try using SPF for filtering inbound mail. On the up side, a lot of bad mail was being caught. On the down side, it seems like there is always a 'very important' message being caught in the filter because the sender has failed to consider all mail sources in writing their record. At first, I tried to assist sending parties with correcting their records out of hope that it was isolated. This quickly started to consume far too much time. I'm learning that many have set up inaccurate but syntactically valid SPF records and forgotten about them, which is probably the worst outcome for SPF as a standard. Are you using SPF? How are you handling false positives caused by inaccurate SPF records?"