The Queen of Direct Mail Marketing ... Barbara Todaro will have nailed down response for you.  I do not do direct mail these day. I did years ago, 

I send postcards to a farm 6x/year. I think Barbara Todaro  our direct mail guru sends a variety of direct mail must more regularly

About once every 3 or 4 years we send out a mailing.

As others have answered, I won't be able to say it better than Barbara Todaro.  I'm sure you follow her and if for some reason you don't...do something good for yourself and do so immediately.

Market like you mean it.   List.  Sell.  Rinse.  Repeat.      

As others have said...go to Barbara Todaro posts and you will learn everything there is to know about direct marketing!

I gave up mass mailing years ago and it didn't negatively affect my business.

i do mail:

1. House Anniversary card
2. Market Update to my farm and sphere
3. Updates on anything real estate to my sphere and farm
4. Holiday Card
5. Every other month we publish a magazine to our top 100 list

Other than the above, everything else is email.  Many of our clients prefer email so we send the same as above to many more in email format.  Except Holiday, Anniversary or other personalized cards. 

Weekly

Depends on what you consider direct mail marketing. I mail something to my sphere at least monthly.

Nathan Gesner - I think it should be at least once a month. Barbara Todaro knows it all, though...

Monthly, when something is coming on the market, goes under Contract and sells...and holidays!

BUT, don't listen to me; listen to the QUEEN of marketing, Barbara Todaro!

I email quarterly to my investors.

monthly to the entire town.... 

just listed, sale pending and closed will be mailed as the change of status happens.... 

I do monthly with my farm and supplement with just listed and just sold.  If you aren't consistent you can't expect to see results.  I think quarterly just isn't enough to make an impact.  

The default plan is every 2 months. However, that plan is rarely implemented.

I use direct mail at every opportunity I have something to talk about THAT IS RELEVANT TO THE RECIPIENT. In essence, it is EBM.

My farm gets a post card every other month unless there's a new or sold listing -- then they get one about that too.  My A clients get a newsletter every other month too (which I need to get working on!).

Quarterly is completely useless.  You need to consistent beat other agents to get taken notice. This is followed by door knocking, calling.....

Every 3 weeks during peak selling months, once a month afterwards. Break at Christmas.

Frequently and regularly.

Barbara Todaro is the one to ask about this.

Not as much as in the old days.  I'll do some just sold cards now.  Should do some coming soon, just listed in addition to the sold ones.  Coming soon for me is easy, since right now I have three homes under construction that will be coming on the market within the next 1-4 months (some sooner, others not).

I mail 300 postcards to out of state owners each week for property management business

Depends on the purpose I guess.  We have never done postcard mailings. Actually, not true, we did them once during the short sale era, decided it wasn't our thing.  I used to send a quarterly letter to my past and current clients - it wasn't a newsletter, just a letter with market updates, things I'd learned in classes, updated them sometimes on our business, etc.  And we have always send a Christmas card to our entire database and handwritten card throughout the year.  We also used to do an email newsletter every month.  I quit a lot of this when I had kids and just couldn't do it all.  I meant to go back to it when I had more time, but I haven't and it doesn't seem to have negatively affect our business at all, so...-Kasey

Barbara Todaro is the guru on this subject. 

I use email more than mail. Weekly reports and automated searches.

Richard Weeks nailed this one!

Monthly plus just listed and just sold postcards.

My marketing has been very sporadic over the last couple of years with business being so brisk.

At the moment I do not farm. But quarterly for two years min would be my choice if we talk about cold farming. 

Sphlere quarterly,                expir e s  m onthly

Depends on the marketing campaign and the target.  Overall, weekly something is going out.

I use just sold and just listed cards and mail into neighbors occasionally that are ready to turn some listings. I do something about once a month on a small scale.

Nathan,

Each market is unique, and what works in one fails in another.  A

I aim for once a month but probably succeed 2/3 of the time.

Don't direct mail any longer. When I did the mailing went out monthly with postcards for just listed and just sold as necessary.

No direct mail these days.

Montly regular material + weekly Just Listed/Just Solds as I have them