Use MapMarker's built-in address cleaning feature before buying additional software. This is not a separate step, but a built-in part of MapMarker's operation. This is a relatively low cost thing to try. AccuMail and StreetRite are from the same manufacturer and are almost identical in price and features. Call SGSI for details.
Some organizations geocode the addresses as they are entered.
This gives immediate feedback to the entry operator if an address is incomplete, miss-spelled or wrong. A full discussion of the options can't occur here. For rural counties, the improved hit rate with Rev 4 will be more noticeable than in urban counties. StreetInfo Rev 4 has new map layers and is superior to Rev 3 in more ways than simply geocoding success. Cost is roughly double the cost of StreetInfo Rev 4.