Twice every Seven Years

And you shall inscribe them upon the doorposts of your house and upon your gates. [Va'etchanan 6:9]

Now that my shoulder is healing, I am able to do things that I should have done sooner, such as check my mezuzot !  They are supposed to be checked TWICE every Seven Years.

Most people are under the false impression that you are supposed to have them checked once every seven years. The fact is that the Shulchan Aruch (Code of Jewish Law) states that they need to be checked by a scribe twice in every seven year period. That means about every 3.5 years.

The benefits of having a kosher mezuzah on every door post in your home cannot be underestimated.  That means every doorpost, not just the front door [of course with the exception of any room that contains a toilet as such a room is tamei - impure].  And if you have a gate with a lintel over it, that needs a mezuzah as well.  A gate without a lintel doesn't require one.

Make sure the mezuzah is the right way up and the Shin/Daled/Yud is visible on the front.  An upside down mezuzah in its case is not going to work properly.

To learn more about the mitzvah of the mezuzah see here and here.

As it happens, all my mezuzot were kosher, but I decided to buy a bigger newer one for the front door anyway.  The bigger the better.  And it was the Lubavitcher Rebbe who campaigned for bigger mezuzot, as opposed to those tiny little scrolls that everyone used to have when they were trying to hide them from their anti-semitic neighbours.  If, however, you do happen to live in a place where you are worried about anti-semitism, place the mezuzah just inside the front door.  You might want to check with a Rabbi first about this though.

This is one mitzvah you should do, not only because it is commanded of us, but because it gives you incredible protection spiritually and physically.