Note that I am also a real estate agent as well as an investor/builder/developer, so I have multiple ways to monetize a postcard response. 

In a dream world - the comprehensive solution does all this: *task management and sequencing where you can drop a property into a sequence ie day 1 call, day 2 mailer (have it automatically mail out something like a postcard) day 3 etc etc etc*project management outside of the outreach sequences for what's next in the process ie schedule inspection, send the contract, etc etc*ability to have multiple users drive around and if you see a property you can tag an address and add it into a marketing sequence, and also track the streets you've hit so you're not wasting time driving by the same houses more than once *dialer (ability to parallel dial numerous numbers simultaneously to make cold calling more efficient - Ive used tools like orum and kixie in other industries, and when you receive a pickup, the other calls are dropped) *skip tracing/data provider *website landing page for converting online visitors to leads*electronic signature/docusign*secondary branded landing site on different URL for blasts for deal disposition to your buyer listWhat am I missing? 

They waste a TON on money shotgunning postcards and letters out to wholly unmotivated owners until they run out of money.The tip-off is that "buy-box" question.

After I got good at pulling leads that work, I can switch that ratio and spend $3 on leads and $7 on sending something to those leads;  post cards, sms, rvm, cold calling.   

Postcard Mania.  

Offline includes doing yellow letters, post cards, bandit signs, news paper ads, etc.There's an abundance of material on BP regarding all the methods I've mentioned, so just type in the search box which method you'd like to learn more about and learn that method really well before trying other forms of marketing. 

Mailing yellow post cards to cash buyers using a list from list source, post a "ghost ad" on Craigslist.

I've sent out 2250 letters and post cards and gotten 57 responses.  

My recent postcard mailer generated a lead for a 6-unit apartment building in the Elgin area.  

All of which she was doing at the previous company she worked for.I'll also have her do some administrative task like pulling leads/lists for mailings from county websites, ordering postcards, Maybe answering phone calls... haven't decided on that yet.