Direct mail is integral for political campaigns, but there are a few different approaches that can be taken for political mailings.  Many political campaigns saturate areas, mailing to everyone in a specific area.  This has advantages in that the campaign has a wide reach and there are also postage savings as well as the ability to mail larger pieces at similar postage rates.  This is great for some campaigns, but other times a more targeted approach is necessary.

Targeted political mailings can use data from the registrar of voters or other data sources to specifically target voters, interests, or demographics.  One advantage of targeted political mailers is that you can specifically target voters which saves money on postage and printing.  You can also eliminate certain voters and focus on your mailings on your base.  

Targeted political mailings also give you the option of tailoring the message of the mailer to the specific audience.  Lists can be created and/or segmented so a specific message that resonates with a certain group or demographic can be used.  Creating specific messaging for based on data can be much more effective then canvasing an entire area with a generic message.

There are additional costs in using a targeted approach like an increase in postage, possible increases in printing costs due to variable data printing, list costs, increased design costs for different messaging, etc.  Yet, many times these additional costs are offset by the fact that the mailings will be smaller than the saturation mailings so you will spend less on postage and printing.

Both forms political mailings are very effective but the choice as to using a saturation mailing vs a targeted approach will depend on the type of campaign and which strategy is best suited for the campaign and its messaging.  It can also be very effective to use a mixture of generic and targeted mail pieces.